GEMS AND GEM MINERALS
GEMS AND GEM
OLIVER CUMMINGS FARRINGTON, PH.D.
CURATOR OF GEOLOGY, FIELD COLUMBIAN MUSEUM
" FOR LITERAL TRUTH OF YOUR JEWELS THEMSELVES,
ABSOLUTELY SEARCH OUT AND CAST AWAY ALL MANNER OF
FALSE OR DYED OR ALTERED STONES. * * * AND. AS A
PIECE OF TRUE * * * KNOWLEDGE, LEARN TO KNOW
THESE STONES WHEN YOU SEE THEM UNCUT."
A. W. MUMFORD, PUBLISHER
BY OLIVER CDMMINGS FARRINGTON
f)c Eakest'tie $rrse
DONNELLEY & SONS COMPANY
NATURE OF GEMS - 1
OCCURRENCE OF GEMS - 4
MINING OF GEMS - 8
COLOR OF GEMS - 13
SPECIFIC GRAVITY - 19
OPTICAL QUALITIES 26
ELECTRICAL PROPERTIES, PHOSPHORESCENCE, AND FLUORESCENCE 34
CRYSTAL FORM - 37
CUTTING AND MOUNTING 41
VALUATION AND PRICE - 50
IMITATION GEMS AND How TO DETECT THEM 54
SUPERSTITIONS EEGARDING GEMS 57
BIRTH-STONES - 61
CORUNDUM - 88
SPINEL - - 95
EUCLASE - 104
PHENACITE - 105
CHRYSOBERYL - - 106
TOURMALINE - - 111
LEPIDOLITE - - 117
SPODUMENE - - - 118
CYANITE - - - 123
ANDALUSITE - 124
STAUROLITE - 126
GARNET - 127
CHRYSOLITE -- ---132
EPIDOTE - - - - 134
VESUVIANITE - - - - - - - -135
IOLITE - - - - - - -136
EUTILE .... -.-. 137
TlTANITE - 138
AXINITE - - - 139
SAMARSKITE, GADOLINITE, ALLANITE, FERGUSONITE, POLYCRASE, AND
EUXENITE - 140
QUARTZ - - 141
JADE - 165
DIOPSIDE - 168
HYPERSTHENE AND BRONZITE - - 169
TURQUOIS - 170
VARISCITE - 174
CALLAINITE - 174
FELDSPAR - 175
OBSIDIAN - 180
MOLDAVITE - 183
APATITE - 185
FLUORITE - 186
HEMATITE - 188
PYRITE - - 189
CHLORASTROLITE - - - 191
THOMSONITE - - - - -192
PREHNITE - - 193
EHODONITE - - - 194
ZOISITE ... - 195
PRECIOUS SERPENTINE - - 195
MALACHITE - - - 197
CHRYSOCOLLA - - - 199
DIOPTASE - .... 200
LAPIS LAZULI - - - 201
ALABASTER - - - 204
AMBER - - 205
PRECIOUS CORAL - - - - - -221
HALF-TONES AND LINE ENGRAVINGS
ANDALUSITE, SECTION OF CRYSTAL OF - 124
AXINITE - - 139
BERYL, CRYSTAL FORMS OF - 99
BRILLIANT CUT, VIEWS OF 44
CABOCHON CUT, VIEWS OF - 46
CEYLONESE GEM CUTTER, A 42
CONCENTRATION OF GEM MINERALS UPON A BEACH - 6
CORUNDUM MINE, NORTH CAROLINA 93
CRYSTAL AXES - 38
CUBE, OCTAHEDRON, DODECAHEDRON, AND TRAPEZOHEDRON - 39
CUTTING AGATES AT OBERSTEIN - 48
DIAMOND BRILLIANTS, EXACT SIZES OF - - 51
DIAMOND CRYSTALS, COMMON FORMS OF - 67
DIAMOND DIGGING NEAR DIAMANTINA, BRAZIL - 4
DIAMOND MINES OF KIMBERLY, 1872 - 81
DIAMOND MINING, Rio JEQUETINHONHA, BRAZIL - 77
DISTORTION OF CUBICAL CRYSTAL - 37
DREDGING PRECIOUS CORAL - - 221
FAIRY STONES - - 126
FLUORITE, CRYSTAL FORMS OF - - 186
GARNET, CRYSTAL FORMS OF - 127
GLACIAL MAP OF THE GREAT LAKES REGION - - - 89
HEXAGONAL PRISM AND PYRAMID - 40
INSTRUMENT FOR EXAMINING GEMS IN POLARIZED LIGHT - 32
MAP OF INDIA, SHOWING DIAMOND FIELDS - 71
MAP OF DIAMOND FIELDS OF BRAZIL 76
MINING OPAL, NEW SOUTH WALES - - - 163
MOLDAVITE PEBBLES - 183
MOSS-AGATE, INDIA - - - 151
NICOL PRISM, CONSTRUCTION OF - - - - - 30
OBSIDIAN CLIFF, YELLOWSTONE PARK - 181
OPAL MINES, NEW SOUTH WALES - - 163
PATH OF RAY IN DIAMOND CUT AS A BRILLIANT - - -29
PATH OF RAYS PASSING FROM DENSE TO RARE MEDIUM - 28
PEARLS, EXACT SIZES OF, FROM 2 TO 30 GRAINS - - 219
PREMIER DIAMOND MINE, SOUTH AFRICA - 8
PRELIMINARY CONCENTRATION OF DIAMOND-BEARING GRAVEL - 78
PYRITE, CRYSTAL FORMS OF 189
QUARTZ, CRYSTAL FORMS OF - - - 142
QUARTZ, CRYSTAL FORMS OF, PRODUCED BY DISTORTION - 38
REFLECTION OF LIGHT, DIAGRAM ILLUSTRATING - - 26
REFRACTION OF LIGHT, DIAGRAM ILLUSTRATING - 28
REMARKABLE DIAMONDS - 72
ROSE CUT - 46
RUBY-BEARING GRAVEL, NORTH CAROLINA - 90
RUTILE - 137
SEARCHING GRAVEL FOR DIAMONDS, BRAZIL - 78
SECTION OF DE BEERS DIAMOND MINE, SOUTH AFRICA 84
SHELL SHOWING IMAGES OF BUDDHA - - 213
SPECIFIC GRAVITY BALANCE - 21
SPHENE - 138
TABLE CUT 46
TETRAGONAL PRISM AND PYRAMID - 40
TOPAZ, CRYSTAL FORMS OF 120
TOURMALINE MINE, HADDAM, CONNECTICUT - - 115
TOURMALINE MINE, MT. MICA, MAINE - 115
TRAP OR STEP CUT 45
TURQUOIS MINE, NEW MEXICO - 172
X-RAY PHOTOGRAPH OF PASTE AND REAL DIAMONDS - 35
WASHING GRAVEL FOR RUBIES, NORTH CAROLINA 90
ZIRCON, CRYSTAL FORMS OF- - - - -110
LIST OF FULL-PAGE ILLUSTRATIONS IN COLOR
BIRTHSTONES - Frontispiece
Garnet, r Amethyst, Bloodstone, Diamond, Emerald, Agate, Ruby, Sardonyx,
Sapphire, Opal, Topaz, Turquois.
DIAMOND AND CORUNDUM - - 66
Diamond in matrix, Brazil; Diamond in matrix, South Africa; Carbonado,
Bort, Sapphire Crystal, Cut Sapphire, Ruby Crystal, Cut Ruby; Spinel
Crystal, Rubicelle; Spinel Crystal, Balas-Ruby.
BERYL - - 98
Golden Beryl, Siberia; Blue Beryl, Siberia; Blue Beryl, Albany, Maine;
Aquamarine, Connecticut; Aquamarine, Ural Mountains; Emerald in matrix,
TOURMALINE - - 111
Green Tourmaline, Brazil; Green Tourmaline, Haddam, Connecticut; Tourma-
line section, California; Red Tourmaline, Island of Elba; Red Tourmaline,
California; Brown Tourmaline, Gouverneur, New York; Black Tourmaline,
TOPAZ - - 119
Topaz, with Mica and Feldspar, Russia; Topaz, Brazil; Topaz in Rhyolite,
Utah; Topaz, Japan; Waterworn Topaz, Brazil.
GARNET, CHRYSOLITE, AND EPIDOTE - 127
Almandite Garnet, Alaska; Almandite Garnet, cut; Essonite Garnet and
Diopside, Italy; Essonite Garnet, cut; Demantoid Garnet, Ural Mountains;
Demantoid Garnet, cut; Cape Ruby, cut; Pyrope Garnet, Bohemia; Chryso-
lite Crystal; Chrysolite, cut; Epidote, Knappenwand, Austria.
QUARTZ (crystalline) - - 141
Rutilated Quartz, Brazil; Rose Quartz, Black Hills; Smoky Quartz, Switzer-
land; Amethyst, Virginia; Amethyst, Montana.
AGATE - - 154
Banded Agate, Lake Superior; Banded Agate, Brazil; Moss-agate; Clouded
QUARTZ (obscurely crystalline) - 157
Bloodstone, India; Tiger-eye, South Africa; Chrysoprase, Arizona; Agate and
Carnelian, Lake Superior; Jasper, Germany; Ribbon Jasper, Siberia.
OPAL - - 159
Precious Opal in matrix, Queensland; Precious Opal, New South Wales;
Fire Opal in matrix, Mexico; Wood Opal, Idaho; Prase Opal, Germany.
TURQUOIS (New Mexico) - 170
Indian Amulet; Waterworn piece; Turquois in matrix.
FELDSPAR - 175
Amazonstone, Colorado; Labradorite, Labrador; Moonstone, Norway; Sun-
MINOR GEMS - - 183
Chlorastrolite, Isle Royale; Hematite, England; Thomsonite, Lake Superior;
Thomsonite, polished, Lake Superior; Cat's-eye, Quartz, Ceylon; Variscite,
Utah; Moldavite, Bohemia.
SERPENTINE, SMITHSONITE, AND SATIN SPAR - 195
Serpentine, Cornwall, England; Serpentine, polished, Cornwall, England;
Smithsonite. Greece; Satin Spar, Italy; Thulite, Norway.
AMBER, MALACHITE, LAPIS LAZULI, AND AZURITE - - 205
Amber, with inclosed insect, Coast of Baltic Sea; Amber, rolled pebble,
Coast of Baltic Sea; Malachite, Ural Mountains; Malachite, Australia; Mala-
chite, Arizona; Malachite and Azurite, Arizona; Lapis Lazuli, Siberia.
JADE, PEARL, AND CORAL - - 212
Jade, variety jadeite, Burmah; Jade, variety nephrite, New Zealand; Oriental
Pearls; Fresh -water pearl grown to shell; Precious Coral, Mediterranean
Sea; Precious Coral, polished; Chrysoberyl, Russia.
Where do they come from? What are they made of? How can
they be distinguished? What is their value? are questions often
asked with regard to gems, the answers to which must be sought
from widely scattered sources. In the hope of affording means for
answering these questions within concise and convenient limits, the
accompanying work has been prepared. It has been sought in it
to avoid technical discussions; but at the same time the use of scien-
tific terms has not been shunned, since they give increased accuracy.
The subject as a whole has been treated from the mineralogical stand-
point, it being believed by the writer that this affords the best basis
for a thorough knowledge of gems. Each gem is considered under
the mineral species to which it belongs; as, for example, ruby and
sapphire under corundum; emerald and aquamarine under beryl, etc.
It is probable that several gems may not at once be recognized under
this grouping; but on the other hand, such an arrangement is likely
to lead to a knowledge of some now little used.
In the preparation of this book the writings of others have been
freely drawn upon ; and in making acknowledgment of these the writer
would refer the reader to them as means of obtaining information upon
many points of which the scope of the present treatise has forbidden
First should be mentioned the Edelstdnkunde of Max Bauer, a
most elaborate and accurate general treatise upon gems of the present
day. Other useful general works are Emanuel's " Diamonds and Precious
Stones," Church's "Precious Stones," and Feuchtwanger's "A Popular
Treatise on Gems." Kunz's "Gems and Precious Stones of North
America" leaves nothing to be desired in the treatment of this field;
and the annual reports in the " Mineral Resources of the United States "
by the same indefatigable worker serve to convey from time to time the
latest information upon gem matters. Besides the above mentioned,
there are numerous works devoted to special provinces of the study
of gems, which have been and may be consulted with profit. Among
these may be mentioned Buffum's " The Tears of the Pleiades ; " Shelley's
" Legends of Gems," King's "Antique Gems," Streeter's "The Great
Diamonds of the World," Hamlin's " Leisure Hours among the Gems,"
Williams's "Diamond Mines of South Africa," Boutan's "Le Diamant,"
and Tassin's " Descriptive Catalogue of the Collections of Gems in the
United States National Museum," 1902.
To several individuals the writer is under obligations for valuable
assistance. The Foote Mineral Company of Philadelphia kindly loaned
numerous specimens for illustrating the colored plates. Mr. Frederick
J. Essig, of Chicago, rendered similar aid in loaning specimens of cut
stones and photographs, and also gave freely information regarding
many practical points.
To Dr. Orville A. Derby, of the Geological Survey of Brazil, Dr. J. H.
Pratt, Mr. A. C. Lane, Dr. A. C. Hamlin, Ernest Schernikow and Prof.
J. P. Iddings the writer is also under obligation for the loan of photo-
graphs ; and to Dr. P. Groth, of Munich, for the loan of a half-tone plate.
Mr. William K. Higley has given the details of preparation of the
plates and typographical execution of the work much careful attention,
and the writer is indebted to him for other assistance and courtesies.
In conclusion, it is the writer's hope that this work may lead to a
wider knowledge of gems, a more intelligent use of them and an admis-
sion to their charmed circle of some substances now shut out because
NATURE OF GEMS
Gems are minerals prized for their color, hardness, luster, and, for
the most part, transparency. It is generally essential that a mineral
to be a gem should excel in at least three of the above-named properties,
although a few are superior in only two. Some minerals may, for
example, possess desirable color and luster, but, lacking hardness, are
little used for gem purposes, because they would become quickly marred
when worn. Fluor-spar is an illustration of such a mineral. That
a high degree of hardness is not essential, however, to the employment
of a mineral as a gem is shown by the extensive use of such substances
as pearl, amber, jet, and turquois, for gems. All of these are easily
scratched by ordinary objects. It is to be noted, however, that they are
not transparent substances, and that an opaque or translucent substance
may endure, without serious injury, scratches which would be fatal
to the beauty of a transparent gem. Hardness and color alone cannot,
however, make a mineral suitable for gem purposes. This fact is illus-
trated by many varieties of corundum, which have a high degree
of hardness and good body color, but are not used for gems because
not transparent. It is evident, therefore, that no fixed rule can
be assigned for the use of a mineral as a gem, the favor or disfavor
in which it is held seeming, in many instances, to be a matter
of pure caprice.
But, however capricious popular favor may seem to be in its estimate
of the qualities desirable in gems, it may be set down as a fairly general
rule, that the gems which combine the most of the qualities previously
mentioned are those most highly prized. Thus, a red or blue diamond,
excelling as it does all other minerals in hardness and luster, and being
the equal of any in color and transparency, is the most valuable of gems.
The ruby and sapphire excel in hardness, and have good color, luster,
and transparency. They rank among the most valuable of gems.
In speaking of minerals which have desirable gem qualities, it must
not be supposed that this includes all occurrences of any particular
mineral species. On the contrary, only selected portions usually have
the desired qualities. A large part of the yield, even of diamond,
is of no value for gem purposes, though it all finds commercial use
on account of its hardness. Quartz, one of the most abundant minerals
of the earth's crust, though it has the qualities of hardness and luster
suitable for a gem, can be used only in small quantity comparatively for
gem purposes, since only few pieces have the desirable color and
The selection of stones which bear the qualities above mentioned for
purposes of possession and ornament seems to be a taste as old as the
human race itself. In the oldest Egyptian tombs are to be found necklaces
containing emeralds, garnets, carnelians, and other precious stones. The
history of many gems of India dates from a period so remote as to be
indeterminate. The desire to obtain amber led the Phoenicians to make
some of their earliest and longest voyages. Gems were wrought into the
earliest ritual of the Hebrews, and allusions to them are frequent
throughout their Scriptures. The ancient Arabs were familiar with
many of the gems used at the present day, and ascribed to them special
qualities. The Persian turquois mines are known to have been worked
as far back as 1300 A.D., and probably much earlier. There is frequent
mention of gems by Greek writers, and the Romans, especially in the
later days of the Empire, seem to have had great fondness for jewels,
and to have sought them eagerly in their conquests. They used them
in great variety and abundance, and carried the art of cutting and
engraving them to a high degree of perfection.
Moreover, gems are wrought into the history and literature of nearly
all peoples, and furnish standards of color, hardness, luster, etc., which
pass current the world over. Such terms as the " emerald meadow,"
"turquois sky," "adamantine hardness," etc., are derived from the use
of gems, and have universal significance. Advances in civilization seem
to increase rather than diminish the number of minerals used as gems,
the number now employed being larger than ever before in the world's
While it is true that the qualities which have been prized in gems,
and the relative esteem in which they have been held, seem to have
been much the same in all ages, the fashion in gems may vary from time
to time, so that now one stone and now another may take on temporarily
a higher value. Yet, on the whole, their worth varies little among
different peoples and at different times. The principal exception to this
rule is found in the valuation of jade by the Chinese, for they esteem
this above all other precious stones. Aside from a few such exceptions,
gems pass current in nearly all countries at about the same value. They
hence afford to a certain extent a medium of exchange, and are often
made objects of investment, because they are small, portable, and have
intrinsic value. It is not likely that any great excess or diminution
of supply will occur to change the value of the leading gems, such
as diamond, ruby, sapphire, and emerald, as they seem to be distributed
in the earth's crust in but sparing amount. Among the less valuable
gems, great variations in value have occurred, and may again. Thus
the price of precious opal has steadily declined since the discovery
of the Australian fields, although as fine gems are produced there
as were ever known. Topaz and amethyst have suffered a similar
decline in value, while the price of the gem known as " tiger eye "
fell in a few years from five dollars a carat to twenty -five cents
The elements entering into the chemical composition of gems are
not as a rule themselves rare. They are chiefly silicon, aluminum,
magnesium, and other common elements, usually combined with oxygen,
and all abundant constituents of the earth's crust. It is thus not the
rarity of their elements which gives gems their high value, but rather
their peculiar properties as compounds.
Since gems are unequal in value among themselves, many author-
ities distinguish between gems and precious stones, and also subdi-
vide the latter into precious and semi-precious. To the class of gems
belong, according to such a classification, such stones as the diamond,
ruby, sapphire, and emerald; the precious stones include amethyst,
rock crystal, garnet, topaz, turquois, moonstone, opal, and the like;
and the semi - precious, jasper, agate, carnelian, lapis lazuli, amazon
stone, labradorite, etc.'" Since the different kinds and qualities grade
into each other, insensibly however, and no sharp lines can be drawn,
the distinction hardly seems worth making. In. tfre following pages,
therefore, the terms gem and precious stone will be used interchange-
ably, and will be considered to include any mineral, and even some
substances of animal and vegetable origin, which have attained a cer-
tain vogue for purposes of ornament.
OCCURRENCE OF GEMS
It was the opinion of the ancients that gems were largely confined
in their occurrence to tropical countries. Most gems which they knew
were so obtained, India being the chief source of them. Their wise
men reasoned, therefore, that the warmth and light of the sun of the
tropical zone were needed to give gems that fire and brilliancy which
made them precious among stones. With the wider knowledge of the
earth which has been gained in later times, however, it has become evi-
dent that climatic conditions have little or nothing to do with the
occurrence of gems. The greater oxidation produced by the heat of the
sun in the tropics may add to the warmth of color of such stones as
the carnelian and agate, but it would have a tendency to fade the
amethyst and sapphire. A greater abundance of gems in the tropics
may arise from more extensive decomposition of the rocks there, and
this is undoubtedly a favorable circumstance. Moreover, glaciated coun-
tries, such as the northeastern portion of North America, have a soil
composed of too heterogeneous a mixture to favor the search for gems.
So far as the underlying rock is concerned, however, there is not, so far
as we know at present, any distribution by latitudes which favors one
locality over another. Hence the mountain fastnesses of the Urals
furnish gems no less than the broad valleys of India, the bleak shores
of Labrador as well as the steaming jungles of Burmah, and the
barren veldt of the Transvaal as well as the thickly settled valleys
The first discovery of gems in a region is usually made, like that
of gold, in the beds of streams. Often it is in the search for gold that
gems are found, as is illustrated by the fact that the discoveries of diamonds
in Brazil, sapphires in Montana, and rubies in North Carolina were made
in this manner.
The frequent occurrence of gems in the beds of streams is due to the
fact that the gem minerals are usually harder and less easily decom-
posed than the other minerals of the rocks in which they were formed.
Hence they remain after the mother rock has disintegrated and its con-
stituents for the most part removed. The discovery of gems in a stream
bed is further facilitated by the enhancing of their color when wet,
causing them to attract attention. Moreover, the flowing stream tends
to group together minerals of the same specific gravity, thus causing
a concentration of the gem minerals. A stream bed is therefore a good
place to look for gems. Besides the fact that the gems are concentrated
here, and can more easily be seen, a further advantage lies in the
fact that they are likely to be of better quality than those found in
the matrix, since the wear of the stream has opened and separated
them along any little seams that may have existed, and the pieces
left will be of uniform texture and free from imperfections. On the
other hand, a continual reduction in size takes place from the wear
of the stream, and larger gems will therefore be obtained by search-
ing the mother rock. The quantity of any given gem is likely, too,
to be limited in a stream deposit as compared with the deposit in
place ; and just as with gold, the mother lode must eventually be sought
if a permanent supply is desired.
It must not be supposed, however, in speaking of stream-bed deposits,
or " gravels," as they are usually called, that only gravels over which
water is now flowing are meant. Beds of earlier streams will afford
the same products and the same facilities, with the exception that
the color of the precious stones will not be so obvious. It is evident,
too, that in any particular gravel the quantity, size, and variety of the
gem minerals present will depend not only on their quantity and variety
in the original rock mass of which they formed a part, but on the
length of time they have been exposed to wear and the rate of flow
of the stream.
In the so-called gem gravels, numbers of gem minerals are usually
associated together. Thus, in those of Ceylon are to be found sapphire,
tourmaline, zircon, garnet, spinel, iolite, and many others; and in those
of Brazil, topaz, chrysoberyl, andalusite, and others. Quartz, garnet,
and beryl are frequent constituents of gem gravels, as well as the
heavier minerals ilmenite, rutile, and magnetite. The knowledge that
garnets usually accompanied diamonds in the " wet diggings " along
the Vaal River led to the discovery of the " dry diggings " at Faure-
smith, in South Africa, and in other cases a knowledge of the min-
erals usually associated with a gem has been of great aid in discover-
ing the gem itself. This grouping together of the gem minerals arises
from the fact that they are not only formed together in the original
rock mass, but also that they are of about the same hardness, and
to a certain extent, specific gravity.
The beaches of lakes, or of the sea, also afford places for the gather-
ing of gems by processes similar to those just described. By wave
action and currents the cliffs of the shore are continually being worn
down, and the lighter and finer particles borne sea-ward, while those
which are heavier, either because of higher specific gravity, or of greater
resistance to erosion and decomposition, and hence larger, remain behind.
A continual concentration is thus going on which in time may pro-
duce gem deposits of some extent. The area upon which such a depo-
sition may take place is, however, relatively narrow at any one period,
as compared with that afforded by streams, and hence few gems are
likely to be obtained from such sources. Labradorite and hypersthene
are obtained from deposits of this character upon the coast of Labrador;
chlorastrolite from the shore of Isle Royale ; and agate and thomsonite
from beaches of Lake Superior. Hardly any other gem minerals can
be mentioned as so obtained, with the exception of amber, which is
gathered from the coast of the Baltic Sea. This, however, is deposited
not through its heaviness but its lightness, it being borne upon the
waves and tossed inland.
Passing from the gravels in which gems are found to a consideration
of their original rock matrices, it may be said that rocks of the kind
known as metamorphic are more commonly than any others the home
of the gem minerals. Metamorphic rocks are those which have been
changed by heat and pressure, or chemical agencies, from their original
condition. They include crystalline limestones, quartzites, mica and
hornblende schists, gneisses, eclogites, etc. The rubies of Burmah, the
emeralds of the Urals, the diamonds of Brazil and the garnets of the
Alps are illustrations of gems which occur in this way.
Next to metamorphic rocks those of an eruptive character afford
the gem minerals in the greatest abundance. Of these the acidic
rocks, i. e., those containing a relatively large quantity of silica, such
as the granites, trachytes, rhyolites, and syenites, are the most prolific.
The coarsely crystallized form of granite known as pegmatite is espe-
cially fertile in the gem minerals. The basic eruptive rocks, i. e., those
poor in silica, afford among gem minerals, chrysolite, some garnet,
some corundum, vesuvianite, and a few others. They are, however,
comparatively barren. The diamonds of South Africa occur in a rock
seeming to be of a basic eruptive character ; but whether the diamonds
are of primary or secondary origin is not yet known.
Of all the great groups of rocks those of sedimentary origin furnish
the fewest gems. Those which do occur in these are for the most
part probably derived from older eruptive rocks. Such is believed to be
the origin of the emeralds of Colombia, which are found in a bitumi-
nous limestone of Cretaceous age. The opals of New South Wales, how-
ever, occurring in sandstones and limestones of Tertiary age, doubtless
were formed in place, and owe their deposition to the circulation
of siliceous waters through the rocks.
The distribution of gems through a rock or gravel matrix is not
usually uniform. The gems more commonly occur in pockets, so called,
the location of which seems to be governed by no law as yet dis-
covered. Where crystallization of minerals has taken place about
a fissure or open cavity, the minerals are more likely to be clear
and free from inclusions than where formed in the mass of the rock
MINING OF GEMS
The methods employed in the mining of gems depend obviously
upon the occurrence of the latter. If occurring in gravels, or decom-
posed rock areas, as is the case with the majority of gems, mining
usually takes the form of open cuts, made either by digging numerous
small pits, or one of extensive dimensions. The separation of the
gems from the common pebbles accompanying them is then performed
by some method of washing, usually hand panning combined with hand
picking. Panning depends for its operation upon the generally high
specific gravity of the gem minerals as compared with those of com-
moner occurrence, and is thus similar in principle to gold panning.
The utensil most commonly employed is a shallow pan of wood or
metal, from 12 to 18 inches in diameter, and of a more or less coni-
cal shape. On taking up a quantity of the gem-bearing gravel in this
with water, and rinsing the whole with a circular motion, the lighter
minerals fly off and the heavier concentrate toward the center. After
the contents of the pan have in this manner been considerably reduced,
by searching and hand picking any gems which may have gathered
at the center can usually be readily seen and picked out.
Of the methods of mining and separating gravels by hand digging
and panning, the procedure of the Cingalese in exploiting the Ceylon
gem gravels may be considered a good illustration. These methods
are thus described by Dr. A. C. Hamlin :
"The mining operations are generally carried on by the native
Cingalese, who labor in the light of a pastime, and only during inter-
vals of their agricultural employments. Some few, however, undertake
the labor as a regular business, but they belong to a low and dissipated
class, and do not work systematically or with regularity. Therefore,
the gem -mining of Ceylon cannot be regarded as a fixed and per-
"When an exploration has been determined upon, a small party
of villagers set out for the promising region provided with the imple-
ments of mining and the means of camping out. The times selected
for the operations are after the heavy rains, which prevail in June and
October, and the floods have subsided. The beds of rivers, or smaller
streams, are often chosen as easier of access than the plains. If the
river-bed is selected, the first act of the explorers is to seek for the
proper locality where the gem-bearing strata may be found. To ascer-
tain this, the Cingalese thrust a long iron rod of ten or twelve feet
in length into the earth, and test the nature of the sub-soil. By means
of long practice the natives can adroitly penetrate the earth to a con-
siderable depth; and, by the resistance to the movement of the rod,
can detect the gem deposit of which they are in search.
"If the indications are good, the natives proceed to build a hut
if they are at a distance from their village, and prepare for the oper-
ations, which often extend over many weeks. After diverting a part
of the force of the stream so as to form a quiet pool, they proceed
to excavate the sand and gravel within a certain area. In order
to accomplish this they use hoes with handles fifteen or more feet in
length. The top strata are hurriedly raked up and thrown away;
but as the pit deepens and the gem stratum is approached, the work
is performed with greater care. As soon as the hoes bring up frag-
ments and boulders of white quartz, or strike thin ferruginous crust,
every particle of the gravel drawn up is carefully preserved. The
gravel and sand thus obtained are then placed in large baskets woven
of split bamboo and shaped to a conical point at the bottom. The
basket thus filled is placed in the current of water, and its contents
washed by imparting to it a circular motion. This washing process
is kept up until the stones, gravel, and lesser particles are cleansed.
During this operation the gems, which are much heavier than com-
mon stones, settle at the bottom of the basket, and are there collected
together, so that when the superincumbent gravel is removed, the
sapphires, garnets, zircons, etc., are easily discovered at the bottom
and removed. This is the manner in which the wet diggings are
carried on, and is the easiest mode of exploration; but it is by no
means as sure, or often as profitable, as the operations in dry ground
on the river banks or in the plains. The dry diggings are much more
laborious, as the soil is firmer, and the gem strata must be trans-
ported to water to be washed and sifted. These dry deposits are
found the richest beneath the alluvial plains, which seem to have
been in distant times shallow lakes and lagoons.
" The gem stratum, called mellan, is always well defined, and occurs
at a certain depth, which seems to correspond to the bottom of the
lake at a definite period. This depth varies from two to twenty feet,
and is perhaps even greater; but the natives rarely excavate below
the depth of twenty feet. This peculiar formation, which is generally
horizontal, is composed of a conglomerate of quartz gravel resting upon
or mixed with a stiff clay, often indurated by a ferruginous oxide. In
among this cascalho, or just below it and adhering to it, are found
the fine pebbles and crystals of sapphire, tourmaline, garnet, zircon,
spinel, and chrysoberyl. Under these rocks, and in peculiar hollows
in the plastic clay, which the natives call ' elephants' footsteps,' the
gems are found clustered together heterogeneously, and often so per-
fect in form as to appear as though created there. At other places
they are collected together in these pockets, in such a manner as to sug-
gest the idea that they had been washed in by a current of water."
An account of the methods of gem mining in Brazil, which in many
respects are similar to those above described, will be found in the
chapter on the Diamond in this work. Such methods may be con-
sidered typical of the mining of gems on a small scale. Their success
will obviously largely depend upon the skill and care of the individual
miner. In countries where hand labor is cheap such methods can
usually be conducted with better profit than can be afforded by the
use of machinery. This will especially be true if the gem deposits
are, as is often the case, scattered over a wide area and are irregular
The part of the operation of gem mining to which some form
of machinery or apparatus can usually be most profitably applied,
is that of washing or concentration.
The machines employed for this purpose may vary from the crude
"baby" of the South African Vaal River miner to the elaborate jigs
and pulsators of the Kimberley mines.
Most of these methods are patterned after those of gold placer min-
ing, and depend for their success upon the same principle.
The mining of sapphires in Montana affords an illustration of a com-
bination of several methods of washing, which typifies what may be done
in this manner. It is thus described by Mr. George F. Kunz in the
Mineral Resources of the United States for 1901 :
"The methods employed are a curious combination of those of the
California gold-workings and the South African diamond mines. As in
the latter, the gangue of the gems is an igneous rock, hard below
but decomposed above, in varying degrees, to a mere earthy mass
at the surface. From this last the gems are separated by washing
and sluicing, much in the manner of placer gold; though, because
of the less density of sapphires, more care is necessary, and the sluice
boxes must be less inclined, to prevent the gems from being carried
over the riffles. Most of the New Mine Syndicate's workings are sur-
face openings and cuts, some of the latter very extensive. Water
is carried from Yogo Creek, ten miles distant, by a ditch and flume,
with a parallel hydraulic pipe line; and a system of sluices extends
all along the company's workings.
"Where the rock is much decomposed, the hydraulic process is
employed largely; as it becomes harder, power is necessary to break
it up. Then the rock is thrown out in dumps and allowed to disin-
tegrate by exposure to the weather, as with the African "hard blue."
This process requires from a month to a year, according to the con-
dition of the material. Sometimes a stream of water is turned on
the dumped rock, and the process thus expedited. When sufficiently
decomposed, this material is subjected to the same washing process
as the material naturally disintegrated.
"In the washing the fine earth is carried away with the water;
all hard lumps remaining are again thrown out on a dump to decom-
pose further; and the sapphires, after several screenings, are picked
out by hand."
An interesting discovery made in South Africa, in connection with
the process of sorting diamonds by concentrating them on percussion
tables, was that if the tables were covered with thick grease the
diamonds, and even other precious stones, such as rubies, sapphires,
and emeralds, would adhere to the grease and be held, while the value-
less ingredients of the rock would pass by. The grease can be used for
this purpose for only a few hours when it must be scraped off and a
new coat applied. This, however, is a small disadvantage compared
with the great gain afforded by the selective power of the " greaser,"
as it is called.
Mining for gems by methods of tunneling, shafts, and other means
employed in deep mine workings is rarely carried on. In the first
place, gems do not often occur in definite veins as do the precious
metals, being more commonly irregularly distributed in pockets through
the rock. In the second place, little really systematic mining of gems
is carried on. As a rule, the occupation is, or has been, a rather desul-
tory one. A find of a few good stones leads to temporary search and
exploration, lasting for a few years perhaps, then the work proves no
longer profitable and is abandoned until new finds arouse * new hope
and revive the industry.
The element of fortune, good and bad, seems to prevail more largely
in the mining of gems than in even that of the precious metals. In
gem-mining, as in that for gold and silver, great labor and little reward
go side by side with little labor and great reward. Moreover, the dis-
tribution of gems is exceedingly irregular, and their market price varies
within wide margins, from circumstances of fashion, supply, general
financial conditions, etc.
Yet these contingencies might doubtless be largely overcome by
intelligent and broad-minded management, such as has been conspicu-
ously displayed in the conduct of the diamond mines of South Africa.
Not only is the mining here conducted according to the most approved
systems of modern engineering, but equal attention is paid to placing
the gems upon the market, so that an over-supply shall not reduce the
price. Some further account of this will be found in the chapter on
Regarding the influence of increase of depth upon the distribution
and quality of the gem minerals, no principles have been established
as yet. It is known that veins of amethysts, for instance, have turned
entirely colorless on penetrating below the surface, so that a valuable
stone became with depth worthless. On the other hand, improvement
in color and quality of stones below the surface, as compared with
those above, may often be reasonably expected, since the latter are
more exposed to disintegration and weathering, and the fading effects
In the mining of gems in a small way the amateur is likely to make
the mistake of resorting to the use of too much powder or other
explosive. While the rough work of exploration may wisely be carried
on by means of blasting, the actual removal of the mineral from the
matrix should usually be performed, where possible, by picks and chisels,
in order to avoid the shattering and breaking of pieces suitable for gems,
which often happens in blasting. Many fine gems have been lost through
carelessness in the work of mining, and while not all losses of this kind
can be avoided, with care and patience they can be reduced to a mini-
COLOR OF GEMS
The color of gems is one of the most essential features of their value.
While certain colorless gems, such as the diamond, are highly prized,
even the diamond would lose much of its value if it did not flash
colored lights. So the quality of affording a permanent color probably
leads to much of the esteem in which gems are held. The colors
of the rose and the violet are not less pleasing than those of the ruby
and amethyst, but the former endure but for a day while the latter can
be handed down unimpaired from generation to generation. It was prob-
ably to secure varieties of color that the ancients first used gems, for
their classifications and designations of precious stones were based chiefly
upon this property. With them almost any green stone was known as
emerald, blue as sapphire, and red as ruby or carnelian. This fact makes it
difficult in reading accounts of gems as given by ancient authors to know
what mineral is meant. Distinctions of hardness and specific gravity,
now so much in use, seem to have been ignored by them for the most
part. With the grouping of minerals according to their chemical com-
position, the significance of color largely disappeared as a means of
distinction, since individual specimens of the same composition, and
hence the same species, may vary greatly in color. Usually the quantity
of ingredient required to produce a certain color is too small to be detected
by chemical analysis. That the custom of distinguishing gems by their
colors still survives, however, to a considerable extent, is evidenced by the
fact that different names are still applied to gems of the same mineral
when of different colors. Thus sapphire and ruby are both corundum ;
and emerald and aquamarine are beryl. The mineral quartz appears in
a multitude of colors, to nearly all of which different names are given.
Hence gems of two different names may occur even in the same crystal :
as in a piece of quartz, from one portion an amethyst may be cut and
from another a citrine. On the other hand, different species may pre-
sent stones of exactly the same color. Thus corundum, spinel and garnet
all afford red stones, often nearly alike in tint ; or emerald and tourma-
line both give green stones. Speaking from the mineralogical stand-
point, there are few minerals and fewer gems in which color is a constant
and essential property. Those which may be mentioned as belonging to
the latter class are pvjite, which is biass yellow, lapis lazuli, which is
blue, and malachite, which is green.
In a few cases differences of chemical composition are indicated by
differences of color. This is true of garnet, the magnesium -aluminum
varieties of which are ruby red, the calcium-aluminum varieties brownish
red, and the calcium-chromium varieties green. So tourmaline, when
containing an excess of iron, is black ; an excess of sodium and lithium
is green or red, and an excess of magnesium is brown.
Usually, however, the coloring matter is foreign to the essential com-
position of the mineral, and of very small amount.
This coloring ingredient is in the majority of cases organic matter of
some sort, chiefly hydrocarbons. This has been proved in some cases by
analysis, and in general may be assumed when the color of a stone can
be driven out or changed by heat. The following gems quite certainly
owe their color wholly or in part to organic matter: smoky quartz,
amethyst, yellow topaz, golden beryl, zircon, rubellite, and amazon stone.
The coloring ingredients of the following are chiefly inorganic : ruby,
sapphire, spinel, and emerald.
Next to organic matter metallic oxides are probably the most preva-
lent coloring ingredient. These oxides may occur in scales large enough
to be seen with the naked eye, as is true of the hematite in sunstone, or
they may be only visible with the microscope, as the same substance can
be seen coloring jasper and carnelian. More commonly the coloring mat-
ter cannot be discerned as a distinct pigment. Beside oxide of iron as a
coloring ingredient, chromium, copper and nickel oxides occur, producing
in general green colors. Manganese oxide often gives purple or flesh colors.
By producing some chemical change it is often possible to alter the
color of a mineral. In the case of minerals colored by hydrocarbons,
these changes may best be produced by heating. In this manner smoky
quartz can be changed in color to yellow, yellow topaz to pink, and
brown carnelian to red.
Amethyst, hyacinth, and golden beryl lose their color entirely if heated
any length of time, and smoky quartz may also be made colorless by
long continued heat. Some gems change in color on heating, but regain
it again when cooled. Thus pyrope turns darker on heating, but returns
to its normal color on cooling. Ruby becomes colorless, but on cooling
changes through green to its original red.
Some colors of gems fade or change on exposure to light, a peculiarity
which is of course considered detrimental to their value. In this manner
the blue of turquois may change in time to green, and yellow topaz,
chrysoprase, and rose quartz may lose their color entirely.
Some gems are of a different color by artificial as compared with day
light. The beauty of some may thus be enhanced by artificial light and
that of others weakened. The gem in which the most striking change is
thus produced is chrysoberyl of the variety known as alexandrite. This is
green by daylight, but red by artificial light. Most yellow stones appear
nearly colorless by artificial light because the excess of yellow rays in the
latter makes those from the stone almost invisible. For the same reason
violet stones are likely to lose much of their color in artificial light.
One of the points of superiority of the emerald is that it is able to retain
its color in all lights. The color of the ruby is deepened and made more
brilliant by artificial light, and turquois of good color has its effect
enhanced by the same.
LIST OF GEMS ACCORDING TO COLORS.
Gadolinite, Samarskite, etc.
Corundum (Oriental topaz).
The luster of gems is one of their important and distinctive char-
acters. Not only does it form one of the easiest means of distinguish-
ing gems, but it is also one of the most reliable characters sought by
those experts who depend for their determinations of gems on ocular
examination alone. One familiar with the luster of quartz, as com-
pared with that of diamond, for example, is in little danger of
confusing the two, for the luster of one can be recognized as
adamantine, that of the other as vitreous. The luster of a gem is pro-
duced by the light which it reflects back to the eye, and this may
vary in quantity and quality with the nature of the surface. Since the
latter is largely the result of the molecular structure of the mineral,
it follows that different species will have distinctive luster. The terms
used to describe the different kinds of luster are derived from that
afforded by some well-known object. Thus adamantine luster means
the luster of the diamond; vitreous luster, the luster of broken glass;
oily luster, the luster of oil; waxy luster, the luster of wax; resinous
luster, the luster of resins ; pearly luster, the luster of pearl ; silky luster,
the luster of silk ; and metallic luster, the luster of shining metals.
Of the above kinds of luster, the vitreous is the most common among
gems, being displayed by quartz, topaz, beryl, tourmaline, sapphire, and
many others. The adamantine luster belongs almost exclusively to the
diamond, although it is displayed to some extent by sphene and color-
less zircon and is suggested by some sapphire. It is characteristic
of minerals of a high index of refraction. Metallic luster is strictly
possessed only by opaque minerals, and hence among gems is confined
to pyrite and hematite. The luster of turquois is of the waxy order.
Essonite displays a somewhat resinous luster, and chrysolite an oily
one. Pearly luster is best seen in the pearl, but is also illustrated
by moonstone and opal. Tiger eye and cat's eye afford examples
of silky luster.
Tests of hardness afford one of the most useful and convenient means
of distinguishing gems. Such tests can be easily made and are very
reliable, the hardness of species being remarkably constant. Hardness
should not, however, be confounded with toughness, i. e., the difficulty
with which a mineral can be broken, since many brittle minerals have
considerable hardness. Hardness is rather the power of resistance to
scratching which a mineral possesses.
It is evident that a high degree of hardness must be an important
property of precious stones, as their polish would soon disappear if they
were easily scratched.
The common method of stating the hardness of a mineral is by
referring it to its place in the scale devised by the German mineralo-
gist Mohs. The divisions of this scale are constituted by ten rather
common minerals, arranged according to their hardness. The scale
is as follows :
1. Talc. 6. Feldspar.
2. Gypsum. 7. Quartz.
3. Calcite. 8. Topaz.
4. Fluorite. 9. Corundum.
5. Apatite. 10. Diamond.
To assist in remembering the minerals of this scale in their order,
the following mnemonic has been devised:
Tall Gipsy Girl Flew Up
Talc. Gypsum. Calcite. Fluorite. Apatite.
Fells Queer To Go Die
Feldspar. Quartz. Topaz. Corundum. Diamond.
The position of a mineral in this scale is determined by the minerals
which it scratches. Thus if a mineral scratches feldspar, but is scratched
by quartz, its hardness would be stated as 6.5. In order to test hard-
ness, pieces of the minerals of the scale should be at hand. Fragments
of the mineral to be tested may be grasped in the fingers and rubbed
upon a polished surface of the minerals of the scale, or the test can
often be more accurately made by rubbing upon the mineral of the scale a
coarse powder of the mineral to be tested, by means of a soft pine stick.
With a little practice one may become so good a judge of the hard-
ness of a mineral, by its behavior towards an ordinary pocket-knife,
that the minerals of the scale below 7 may be dispensed with. Thus
minerals of the first two degrees of hardness may be scratched with
the finger nail ; No. 3 can be deeply scratched with a knife ; No. 4 less
deeply and easily ; No. 5 still less so ; while No. 6 is about the hardness
of the knife. No. 6 also scratches ordinary window glass. Upon No. 7
a knife blade makes no impression, the steel rubbing off on the mineral.
Steel of the hardness of a file, however, scratches quartz slightly. These
tests are especially useful for distinguishing glass imitations from gems
of the hardness of quartz and higher. Instead of a file it is well
to use a point of hardened steel to avoid danger of injuring delicate
gems. Rubbing the gem, especially if cut, with an aluminum pencil?
is a still better means of testing hardness in the higher numbers of the
scale, as it involves no danger of injury to the stone. Upon soft
stones such a pencil leaves a conspicuous mark, but upon hard ones none
whatever. Minerals above 7 in hardness are harder than a file. Corun-
dum scratches all minerals except diamond, and diamond is the hardest
Some minerals, if crystallized, are somewhat harder in one direction
than another, the mineral cyanite being a notable illustration of this.
Ordinarily, however, the hardness of a mineral is about the same in
Table showing hardness of gem minerals :
Diamond - - 10 Epidote 6.5
Corundum (Ruby, Sapphire, etc.) 9 Prehnite - - 6.5
Chrysoberyl 8.5 Pyrite - 6.5
Topaz 8 Feldspar (Amazonstone, Moon-
Spinel (Balas Kuby) - 8-7.75 stone, Labradorite, etc.) - 6
Phenacite - 7.75 Turquois - 6
Beryl (Emerald, Aquamarine, Diopside - - 6
etc.) - 7.75 Nephrite 5.75
Zircon (Hyacinth) - 7.5 Opal - 5.5-6.5
Euclase 7.5 Moldavite - 5.5
Staurolite - 7.5 Obsidian - - 5.5
Andalusite - 7.25 Hematite - 5.5
lolite - 7.25 Sphene - - 5.5
Tourmaline - 7.25 Lapis Lazuli 5.5
Garnet - - 7 Hauynite - 5.5
Quartz (Amethyst, Rock Crystal, Cyanite 5-7
Jasper, etc.) - 7 Dioptase - - 5
Jadeite - - 6.75 Fluorite - 4
Axinite 6.75 Malachite - 3.5
Chalcedony (Agate, Carnelian, Jet - 3.5
etc.) - 6.5 Amber - - 2.5
Chrysolite - 6.5 Gypsum (Alabaster, Satinspar,
Vesuvianite - - 6.5 etc.) 2
The specific gravity of mineral species is also one of their funda-
mental and constant characters, and furnishes a reliable means of dis-
tinguishing between gems of different kinds, and of separating false
from real stones. To be sure, a variation of composition may cause
a variation of specific gravity in the same species; but this is usually
within comparatively narrow limits. The different kinds of garnet,
or of tourmaline, for example, possess specific gravities varying within
one integer; but the varieties are usually distinguished by colors by
which the appropriate specific gravity can be judged. One great advan-
tage of using specific gravity as a means of identifying gems is, that the
determination can be made without danger of injuring the stone, which
is more than can be said of tests of hardness, fusibility, or behavior
with acids. While specific gravity can usually be used for distinguish-
ing between gems, as, for example, between quartz as compared with
diamond, it cannot always be used for identifying glass, since by the
addition of different ingredients it is possible to make glass of vary-
ing specific gravity, and similar to that of the gem which it is sought
The specific gravity of a substance is its weight as compared with
that of an equal volume of water. When it is stated that the specific
gravity of topaz, for example, is 3.55, the figures simply mean that
a given volume of topaz is 3.55 times heavier than the same volume
Various means may be taken to determine the specific gravity of a body,
the most obvious and simple depending upon the fact that a body heavier
than water loses, when weighed in that liquid, a weight equal to that
of an equal volume of water. Hence by weighing a body first in
air and then in water, and dividing the weight in air by the differ-
ence between the weight in air and the weight in water, or in other
words, by the loss of weight in water, the quotient will be the specific
The following example of a determination of the specific gravity
of a sapphire will illustrate this:
The weight in grams in air was - 12.89
The weight in grams in water was 9.68
Difference - 3.21
12.89 -r- 3.21 = 4.015, the specific gravity.
A similar quotient will be obtained whether large or small pieces
are taken for determination, the specific gravity being totally inde-
pendent of the actual gravity or weight.
The determination of the specific gravity of gems or minerals becomes
then a question simply of manipulations by which the relative weights
of the substance in water and air can be obtained in the easiest and
most accurate way.
The most common and generally the most convenient way of doing
this is by obtaining the weights of the stone in water and air directly
by means of a delicate balance. The stone is first weighed in air
and the weight recorded. It is then put into a holder of fine plati-
num wire, bent into a spiral form, and suspended from the arm of the
balance. The length of the wire is such as to allow the stone to become
completely immersed in a vessel of water supported on a stand above the
scale pan, but in such a manner as to allow the pan to swing free. In
this way the weight of the stone and wire in water can be accurately
taken. The stone is then removed, and the wire weighed suspended
in the water as before. The weight of this is subtracted from the
previous weight, so as to remove the weight of the wire from the
calculation, and the remainder is the loss of weight of the stone in
water. Dividing the weight of the stone in air by this remainder
gives, as stated above, the specific gravity. Several precautions need
to be taken to insure accurate results. In the first place, only dis-
tilled water should be used, as ordinary waters have higher density.
Again, bubbles of air often adhere to the surface of the stone, especially
if it be rough, or if it is pervaded by cracks, which would obviously,
if allowed to remain, lessen the weight. These can sometimes Be
removed by dipping the stone in water several times and blowing
the water off, or they can surely be destroyed by boiling for a few
minutes the water in which the stone is immersed, and then allow-
ing it to cool before the specific gravity is taken.
Strictly speaking, the specific gravity of a body is its weight
compared with that of water at the temperature of 4 Centigrade
(39.2 Fahrenheit), which is the point at which the density of water
is the greatest. Determinations at other temperatures should, therefore,
if absolute accuracy is desired, be corrected to 4 C. In practice, however,
the error is so trifling that it may be disregarded in all ordinary deter-
minations, especially if the temperature of the water is no higher than
that of the ordinary living-room, say 60 F. (15.6 C.)
In case an accurate balance cannot be obtained, a beam balance
described by Professor Penfield, and shown in the accompanying cut,
can be constructed by almost any one. This gives sufficiently accurate
results for all practical purposes. It consists of a beam of wood sup-
ported on a fine wire, or needle, at o. This must swing freely. The
long arm, oc, is divided into inches and tenths, or into any decimal
scale, commencing at the fulcrum, o; the short arm carries a double
arrangement of pans, so suspended that one of them is in the air and
the other in water. A piece of lead on the short arm serves to almost
balance the long arm ; and, the pans being empty, the beam is brought
Specific Gravity Balance
to a horizontal position, marked on the upright, near c, by means of
a rider, d. A number of counterpoises of different weights are needed.
These may be pieces of bent wire, or bits of glass tube, with a wire
hook fused into one end, g, some of them containing one, two, three,
or more shot, so as to give a variety of weights. The beam being
adjusted by means of the rider, c?, the stone or mineral which it
is desired to test is placed in the upper pan, and a counterpoise is
chosen, which, when placed near the end of the long arm, will bring
it into a horizontal position. The weight, TFa, of the mineral in air,
is given by the position of the counterpoise on the scale. The min-
eral is next transferred to the lower pan, and the same counterpoise
is brought nearer the fulcrum, o, until the beam becomes again hori-
zontal, when its position gives the weight, Ww, of the mineral in water.
Then Wa divided by Wa Ww, gives the specific gravity.
A quick, convenient, and accurate means of separating minerals, and
especially cut stones, according to their specific gravity, is afforded by use
of the so-called heavy liquids. The employment of these depends upon
the fact that a substance will float upon the top of a liquid of greater
density than itself, will remain suspended in a liquid of exactly the
same density as itself, and will sink to the bottom of a liquid of lower
density than itself. Now, a number of liquids are known which are
considerably heavier than water, but whose specific gravity may be low-
ered very gradually by the addition of water or other liquid to them.
If a stone placed in one of these liquids remains floating it is lighter
than the liquid. By reducing the density of the liquid a point may
be reached where the specific gravity of the two is equal, and the
stone will remain suspended somewhere within the liquid. Ascertain-
ing the specific gravity of the liquid gives, therefore, that of the stone.
Or of two stones supposed to be identical, if one sinks in the liquid
as it is gradually diluted, long before the other, a considerable differ-
ence of specific gravity is indicated, and the stones are doubtless
of different species. Here, as in making determinations of specific
gravity by weight, the relative size of the stones does not need ordi-
narily to be taken into consideration.
The heavy liquids principally employed for the above purposes are
the following: A. solution of potassium mercuric iodide, known
as Thoulet's or Sonstadt's solution, having a specific gravity of 3.15;
methylen iodide, whose maximum specific gravity is 3.32; and silver
thallium nitrate, which on fusing yields a liquid with a maximum
specific gravity of 4.5-5. The first, or Thoulet's solution, is prepared
by treating five parts by weight of mercuric iodide and four parts
by weight of potassium iodide in a porcelain dish with a little water
and evaporating until a crust begins to form. The solution can then
be reduced to a desired density by adding distilled water, or can
be brought back to the maximum specific gravity by evaporating the
water. It can be kept indefinitely if placed in closely stopped bottles,
especially if a few drops of mercury be added. It is poisonous. In
using it, steel pincers or glass rods should be employed for immersing
the stones, as the insertion of brass instruments causes a decomposition
of the liquid, and a deposition of mercury upon the metal.
While the Thoulet solution is the cheapest and easiest of the heavy
liquids to manipulate, its rather low density prevents its use for gems
having a specific gravity much over 3, and hence some of the other
liquids are often preferred. Methylen iodide is recommended by Bauer
as best suited for the general purposes of the student of gems. This
has, as stated, a maximum density of 3.32; but by saturating with
iodine and iodoform a density of 3.6 may be obtained. The useful-
ness of the latter mixture is somewhat impaired, however, by its very
The dilution of methylen iodide is performed by means of benzol
rather than by water. Bauer recommends having for use four differ-
ent strengths of the liquid, which may be preserved in four labeled
bottles side by side. By dropping the stone whose specific gravity
it is desired to test, into different bottles successively, its specific gravity
can be learned within narrow limits. It is recommended to place in the
first bottle a solution of methylen iodide saturated with iodine and
iodoform. Its specific gravity would be 3.6. The second bottle
should contain pure methylen iodide, marking a specific gravity
of 3.3. The third bottle may contain the same, diluted until its specific
gravity becomes 3.0, and the fourth the liquid reduced to a specific
gravity of 2.65, which is that of quartz. Topaz and diamond would
then float upon the first liquid, but sink in the second. Hyacinth,
ruby, and sapphire, would sink in all. Beryl, emerald, etc., would
float upon the first three, but sink in the last, and so on.
The bottles containing the solutions should be kept tightly stoppered,
as any evaporation affects the density of the liquid. Methylen iodide
is a somewhat expensive chemical, costing, as it does, $1.25 an ounce;
but when a supply is once obtained it will last almost indefinitely.
Instead of having solutions of different densities at hand, some pre-
fer to have ready for use fragments of minerals of different densities
arranged in series. These are called indicators, and are used by placing
one or more in the liquid with the stone whose specific gravity is desired,
and diluting until the indicator sinks or rises at the same time with
the unknown mineral. The unknown mineral must then be of the
same specific gravity as the indicator.
For minerals with a specific gravity above 3.6, the only heavy liquid
available is silver thallium nitrate. This, as previously stated, fuses
to a clear liquid having a density of 4.5 to 5. The temperature required
for fusion is about 75 Centigrade (167 F.), and the work can be con-
veniently done by heating the salt in a beaker upon a water bath.
The dilution can be performed by adding hot water. The necessity
of working always with hot liquids is of course a drawback to the
use of this substance, and it is also a costly chemical. In other
respects it answers well the purposes of a heavy liquid. It should
be noted in the use of all the heavy liquids that the addition of a very
small amount of water, or other diluting liquid, is sufficient to consid-
erably reduce the specific gravity. Hence, the addition of the diluting
liquid should be made very slowly and carefully, with frequent stirring,
and a constant watch on the position of the stone that is being tested.
For the purpose of determining exactly the specific gravity of the
liquid at any point, some form of balance is usually employed, that
known as Westphal's giving quick and accurate results. It is, however,
a somewhat expensive piece of apparatus, and any one not wishing
to incur such an outlay may obtain results nearly as good with the
beam balance previously described. In its use for this purpose a sinker
in the shape of a cylindrical bulb is suspended from a position marked
by a notch near the end of the long arm. By putting shot in the
pans and using the rider d, the beam is brought to a horizontal
position with the sinker in air. The sinker is then immersed in
the heavy solution, and a weight is selected, which, when placed
near the end of the beam will bring the latter to a horizontal position.
The position of this weight gives relatively the weight of the heavy
solution displaced by the sinker. After washing, the sinker is immersed
in water, and the same weight is placed nearer the fulcrum until the
beam becomes horizontal. The position of this weight gives relatively
the weight of the water displaced by the sinker. The larger weight
divided by the smaller gives the desired specific gravity.
By employing proper formulae, weights of bodies may be found if
their specific gravities be known, or the specific gravity of one, if its
weight and the weight and specific gravity of another be known.
Thus if a diamond is set in a gold ring, it is often desirable to know
the weight of the diamond, or its specific gravity, or the specific gravity,
and hence the fineness, of the gold of which the ring is composed, with-
out removing the stone. Each of these values, and even others, can be
found by employing the following formulae. These are derived from
two equations in which A represents the weight of the stone, a its specific*
gravity; B the weight of the gold, and b its specific gravity; and C the
combined weight of the ring and stone, and c their specific gravity.
Then A + B = C
a b c
Whence we obtain for A,
A = C ( b c ) a
(b a) c
for a, Abe
C(b c) + Ac
for b, i _ B a c
= C(a c) + Bc
and expressions for other factors if desired.
TABLE SHOWING SPECIFIC GRAVITY OF GEM MINERALS
Almandine Garnet -
Cape Ruby (Garnet) -
Cinnamon Stone (Garnet)
Spinel (Balas Ruby)
Green and Blue Tourmaline - 3.11-3.16
Red and Colorless Tourmaline 2.94-3.08
Rock Crystal ^
. - 2.65-2.66
Moonstone (Adular) 2.55
Since the pleasing qualities of gems depend largely upon their effects
upon light, some general statements as to the properties of light, and the
manner in which it is affected in passing through gems, will be desirable.
The generally accepted theory of the transmission of light is that it
moves in a straight line without change of direction in one and the same
homogeneous medium, as vibrations of particles of the luminiferous
ether which may be called light waves, and which take place at right
angles to the direction of transmission. In some media the velocity
of transmission of light is independent of the direction in which it is
propagated. Such media are called isotropic, and include among gems,
opal, diamond, spinel, and garnet. In other media the velocity of trans-
mission of light varies in different directions. Such media are said to
be anisotropic. Most gems belong to this class of bodies. The velocity
of transmission of light through different media differs, but has an
absolute value for one and the same substance.
Media in which light is transmitted at a high velocity are said to
be optically rare, those in which it is transmitted at a low velocity are
said to be optically dense. In passing from one medium to another of
different density, as for instance from air into water, light undergoes a
change in its rate of transmission and a change of direction. This change
constitutes the phenomenon of refraction, the most familiar illustration
of which is seen in the apparent bending of a stick
partly immersed in water. If the amount of this
change of direction be studied, it will be found to
have a definite angular value which is constant for the
same substance. Thus, if in the accompanying figure
a ray of light passing through the air from L be sup-
posed to fall upon the surface of water at A, it will be
refracted in the direction A K. The angle L A B is
Diagram illustrating ca u e( j the angle of incidence, and K A C the angle of
refraction of lignt
refraction, B C being a perpendicular to the water's
surface. If from A as a center a circle B C be described, and from the
points ra and p where this circle cuts the incident and refracted rays
the lines ra n and p q be drawn perpendicular to B C, then will
m n be the sine of the angle of incidence, and p q the sine of the angle
of refraction. Now, it is found that whatever the direction of the
incident ray, that of the corresponding refracted ray is so conditioned
that the quotient of the sine of the angle of refraction into the sine
of the angle of incidence is a constant quantity for the same media.
This quotient is called the index of refraction. It is to be found in the
instance above quoted by dividing m n by p q. The greater the refractive
power of the substance the smaller will be the value of p q, and the larger
the quotient, which is the index of refraction. Hence substances with
a high refractive power have a large index of refraction, as diamond,
whose index of refraction is 2.42. That of water is only 1.336. Garnet
has an index of refraction varying from 1.75 to 1.81 in different varie-
ties. Zircon is another gem mineral which possesses a high index of
of refraction, this being 1.96. Diamond is the most highly refractive
of the gems, however.
It is to be noted that the amount of refraction of the different com-
ponent colors of a ray of white light is a variable quantity, and hence in
every refraction the ray is broken up in a way similar to that in which
it is separated into the colors of the spectrum in passing through a
prism. This variation in the refraction of the different colors is called
dispersion. The red waves, for example, suffer less change of velocity
than the blue, and hence the refractive index for a given substance is
greater for blue than for red light. Substances differ in the degree of
refraction which the waves of the different colors suffer in passing through
them, and hence in the degree to which they separate the component
colors ; that is, they differ in what is called dispersive power. Diamond
has high dispersive power, its index of refraction for red light being
2.407+, and for violet light 2.464+, while spinel, which has only an
average dispersive power, has a difference in indices between red and
violet light only between 1.712-f- for red, and 1.726 for violet.
A particular phase of the relations of the incident and refracted rays
should be noted here, as it has much to do with increasing the brilliancy
When a ray of light attempts to pass from a denser into a rarer
medium there are conditions under which the angle of refraction cannot
be greater than the angle of incidence. Under such circumstances the
ray cannot emerge from the denser medium, but will be wholly reflected
at the point of incidence. Thus, in the following figure, if the lumin-
ous rays from A passing out of the water be traced it will be found that
since the angle of refraction increases more rapidly than that of incidence
certain rays cannot emerge at all, but are refracted or reflected back into
Diagram showing paths of
rays passing from a dense into
a rare medium
the water. This is familiarly illustrated in looking into a glass of water
held above the eye, by the fact that the surface of the water appears
to be silvered and opaque, owing to the total reflection of a large num-
ber of rays. The path of the rays is more
fully illustrated in the next figure, showing a
ray of light, L A, passing out of the water by
refraction in the direction A R. If the angle
of incidence, C A L, be gradually increased,
the angle of refraction will also increase, but
more rapidly than the angle of incidence until
it becomes equal to 90, when the ray will
graze the surface of the water at A M. If
the source of light be still further removed as
to Z, the ray can no longer pass out, but is reflected to r. The inci-
dent angle at which internal reflection will thus take the place of refrac-
tion is called for every substance the critical or limiting angle, and is
a constant angle for each different substance. For water (with refer-
ence to air) this angle is 4835', for flint glass 3736', and for diamond
23 53 ' . Substances with a low critical angle or in other words, highly
refracting substances will appear more brilliant than those of low
refractive power, because the amount of light striking upon them becomes
concentrated into a smaller part of the surface.
This can be proved by a mathematical calculation,
but it is too abstruse for these pages. The fact,
however, can be made evident by observation. A
large amount of total reflection, such as is afforded
by substances of high refractive power, has,
moreover, the advantage of returning light to
the eye which would otherwise pass through the
stone and be lost. How this is done is shown by
the following figure after Bauer, representing
the path of a ray of light in a diamond cut
as a brilliant. The ray enters in the direction a b and being totally
reflected from the various points of the interior comes back in some-
what the general direction m g in which it started. It does not come
back, however, as a single ray, but is broken up by the refraction into
its differently colored components. Hence the particular ray which
reaches the eye may be red or blue, or some other color. To this
refractive power, therefore, the diamond owes the property of flashing
colored lights which gives it so much of its beauty and attractiveness.
When refraction, or reflection, of a ray of light takes place, the ray
Diagram illustrating re-
fraction of light at different
undergoes another change, known as polarization. Polarized light is
that having vibrations taking place in a single plane instead of in an
innumerable number of planes, as is the case with ordinary light. A
partial polarization of light occurs with every
refraction and reflection, but it is not complete. By
means of proper appliances a perfect polarization can
be obtained. Polarized light is of great advantage in
the optical study of gems, since it affords a ray the
plane of whose vibrations can be accurately ascer-
tained. Light may be polarized by causing it to be
reflected from two mirrors, and an instrument some-
Path of a ray of light
times used for obtaining polarized light is constructed in a diamond cut as a
.1 . . . i ' rrn i 17 brilliant. After Bauer
upon this principle. Ine most commonly used polar-
izer, however, is the so-called Nicol prism, an appliance constructed from
two pieces of Iceland spar, in a manner which can best be understood
when the subject of double refraction has first been considered.
Light propagated in the anisotropic media previously mentioned,
instead of advancing in all directions with the same velocity, as is the
case with isotropic media, advances in different directions with different
velocities. These directions resolve themselves into two, corresponding
to the directions of the greatest and least elasticity in the medium.
A ray of light entering such a medium is therefore broken up
into two rays, which have distinct properties and move independently
of each other. The refraction of the ray instead of being single,
as is the case with isotropic media, is double, and such media are
hence said to be doubly refracting. To this class belong most gems,
since substances crystallizing in any of the systems except the isometric,
unless they are amorphous, possess this property. The most familiar
illustration of the double refraction of light is seen when an object such
as a black cross upon paper or a line of ordinary print is looked at
through a piece of Iceland spar. The characters when thus seen appear
double, and of only about half their normal intensity, except where two
images may come together. The phenomenon is more evident in Iceland
spar than in other minerals because the two rays are more widely separ-
ated in this substance than is usually the case, but the breaking up into
two rays and the separation take place in many other minerals neverthe-
less. The two rays are known for distinction as the ordinary and extraor-
dinary rays. Each is polarized, so that it is evident that if some means
can be found of eliminating one of them, the other may be made to
furnish a convenient source of polarized light. This is what is done in
the construction of the Nicol prism, it being made of two pieces of
tion of the
Iceland spar cut in definite directions, and cemented together by Canada
balsam. The construction is shown in the accompanying figure. The
parallelogram represents the outline of the prism, and the line running
nearly as a diagonal shows where the two parts are joined
A ray of light, m n, falling upon the prism is at once
refracted into two rays, n and n E. The ray n upon
reaching the layer of balsam is totally reflected, and passes
out at Oj, where it disappears. The ray n E, however,
passes through, and reaches the eye as a ray of polarized
light, having its vibrations in a single plane. If now this
ray fall upon another Nicol prism standing in the same
vertical direction, and similarly oriented, it can pass
through without sensible loss or change, and so on through
a large number if necessary. If, however, the second prism
while maintaining the same vertical direction be rotated 90
about its vertical axis, the ray upon reaching it will follow
the path n instead of n E, since the ordinary and extraordinary rays
are situated at right angles to each other. It will therefore be absorbed
and lost, and no light will reach the eye.
If a plate of a singly refracting substance be interposed between the
two prisms, no change will occur in the above-named phenomena ; but if
a doubly refracting mineral be inserted instead, the field of view will
light up, except in four positions, 90 from each other. It is obvious
that the passage of light through the second prism in the latter case
comes from the fact that the polarized light from the first prism is
broken up into two rays in traversing the doubly refracting plate, one of
which is traveling in such a direction as will permit it to pass through
the second prism. These differences of behavior of doubly refracting
as compared with singly refracting bodies afford a convenient and ac-
curate means of distinguishing gems, for the tests can be made with-
out danger of injury to the stones. The essential features of an
apparatus for the purpose are two Nicol prisms set in a frame one
above the other, with a stage, preferably a revolving one, between.
One of the prisms must be capable of being rotated about its axis.
The lower prism is usually called the polarizer; the upper one the
analyzer. Having turned the prisms with reference to each other so
that the field of view is dark, when a singly refracting substance, such
as diamond, spinel, garnet, or glass, is inserted between the two, no light-
ing up of the field can be observed except such as may come from a
reflection from facets of the object. This reflection should not be con-
founded with an appearance of transmitted light. A doubly refracting
stone will, however, when inserted, be lighted internally, showing much
the same color, though less strongly, as that which it possesses in ordinary
light. On revolving the stone by means of the movable stage, it will
be seen to become dark four times during a complete revolution, the
intervals of darkness occurring every 90 from each other.
Thus quartz may be distinguished from diamond, quartz from glass,
zircon from diamond, or any doubly refracting stone from a glass imita-
tion, and so on. Diamond cannot be distinguished from glass, nor from
spinel, by this test, since all are singly refracting. Other tests, such as
those of specific gravity and hardness, will, however, be sufficient to
distinguish in such cases. It is of course true that stones cut from
doubly refracting minerals in certain directions appear like singly
refracting ones, and a possible error may be made on this account. In
practice, however, the likelihood of meeting with stones cut in just such
directions is very small, and may be ignored. An apparatus constructed
for the determination of gems by the above methods is illustrated in the
following figure (p. 32).* Here the polarization of the light below the
stone is accomplished by means of two mirrors, and thus the cost of
one Nicol prism is saved. The stone is placed upon the stage d. The
light, polarized by the mirrors, passes through the stone into the tube
above containing the analyzer, and through this to the eye. By rotat-
ing the tube in the holder /, the distinction in appearance between
singly and doubly refracting minerals can be readily seen. The ordi-
nary petrographical microscope also affords the necessary appliances
for determinations of this kind. Tourmaline tongs furnish another com-
bination of a polarizer and analyzer, but they allow too little light to
pass through to be of practical value for determining minerals.
Doubly refracting substances have another feature in distinction from
singly refracting ones, in the fact that the rays passing through them are
differently absorbed, and hence give different colors in several directions,
while singly refracting substances are normally of the same color in all di-
rections. In the degree to which they exhibit this property of dichroism,
or pleochroism, as it is called, minerals vary. lolite is one of the most
strongly dichroic minerals, and can plainly be seen to be dark blue in one
direction and clove-brown in another. Transparent zircon is often pinkish
brown in color when looked at it in the direction of the vertical axis, and
asparagus-green when seen laterally. Tourmaline is often nearly opaque
when looked at in the direction of the vertical axis, but transparent when
* This instrument can be obtained of R. Fuess, Steglitz bei Berlin, Germany, at a cost of
eighteen to twenty dollars.
seen laterally. In other doubly refracting minerals the dichroism may
not be sufficiently apparent to be positively observed with the naked eye.
The detection of the dichroic character can usually be made, however,
with the aid of the little instrument known as the dichroscope.* This
consists of an oblong rhombohedron of Iceland spar with a glass prism
Instrument for examining gems in polarized light
of 18 cemented to each extremity, or with the end faces ground and
polished so as to be perpendicular to the length of the prism. It is
placed in a metallic cylindrical case, and is provided with a convex lens
at one end, and a square hole at the other, the focal length of the lens
being such as to show a distinct image of the square opening. On look-
* This instrument can be obtained of Negretti & Zambra, 38 Holborn Viaduct, London,
at a cost of about five dollars.
ing through the dichroscope the square hole appears double, since both
the ordinary and extraordinary ray give an image. If a piece of mineral
or cut stone is held in front of it, two images of this are likewise seen.
These images are of different colors if the mineral is a doubly refracting
one, since the two rays are differently absorbed in passing through such
a mineral. The two images being side by side even slight differences
of color can be perceived. The following are some of the twin colors
exhibited by the more important gems when viewed in this manner, as
stated by Church :
NAME OF STONE , TWIN COLORS s
Sapphire (blue), Greenish straw, Blue.
Euby (red), Aurora-red, Carmine-red.
Tourmaline (red), Salmon, Rose-pink.
" (brownish red), Umber-brown, Columbine-red.
" (brown), Orange-brown, Greenish yellow.
" (green), Pistachio-green, Bluish green.
" (blue), Greenish gray, Indigo-blue.
Topaz (sherry), Straw-yellow, Eose-pink.
Peridot (pistachio), Brown-yellow, Sea-green.
Aquamarine (sea-green), Straw-white, Gray-blue.
Beryl (pale blue), Sea-green, Azure.
Chrysoberyl (yellow), Golden brown, Greenish yellow,
lolite, Pale buff, Indigo-blue.
Amethyst, Keddish purple, Bluish purple.
The dichroscope thus affords a convenient and accurate means of
distinguishing gems. Any one of those in the above list, for example,
could be distinguished from a glass imitation by the fact that any glass
substitute would give two images of exactly the same color, instead of
different colors, as would the genuine stone. Such gems as diamond,
garnet, and spinel cannot, however, be distinguished from glass or each
other in this manner, since they give similarly colored images.
ELECTRICAL PROPERTIES, PHOSPHOR-
ESCENCE, AND FLUORESCENCE
All gems when rubbed upon cloth become, like glass, positively
electrified. Gems differ, however, in the length of time during which
they will retain an electrical charge. Thus tourmaline and topaz remain
electric under favorable conditions for several hours ; but diamond loses
its electricity within half an hour. The electrical peculiarities of differ-
ent species were at one time used quite extensively for identifying
them; but owing to different behavior under different atmospheric
conditions little use is now made of such tests. Besides developing
electricity by friction some gems become electric upon heating. Such
are said to be pyro-electric. To test a stone, or rough piece of mineral
for this property, it can conveniently be held in forceps and heated
gently in a colorless flame, such as that of a Bunsen burner or alcohol
lamp. The amount of heating should not be much over 100 C. On
withdrawing the stone, it will, as it cools, if pyro-electric, attract bits
of tissue paper or straws. Tourmaline is perhaps the most strongly
pyro-electric of the minerals used as gems, and the property affords
a means for identifying it. Topaz is another gem mineral which
usually exhibits this property. Some topaz also becomes electric when
subjected to simple pressure. This is said to be true of some crystals
of Brazilian topaz if they are pressed between the ringers in the direc-
tion of the vertical axis. Electricity developed in this way is known
Simple tests for all these kinds of electricity consist in the attrac-
tion of light objects, such as bits of tissue paper, cat hairs, pith balls
suspended by silk threads, etc. They are best made when the atmos-
phere is dry, the winter season being especially favorable.
Some gems have the property of emitting light after heating, exposure
to light, or an electrical discharge. This property is known as phosphor-
escence, since the glow, although it is often of different colors, resembles
that emitted by phosphorus. The diamond is a mineral which exhibits
this property, some of its gems after exposure to sunlight for a short
time emitting a glow which can be plainly seen in a dark room. This
is often stated to be a property of all diamond, but this is incorrect,
some stones exhibiting no change whatever after exposure to sunlight.
Phosphorescence may also be called out in the diamond by rubbing it,
especially across the fibers of a piece of wood. Among all minerals
phosphorescence is best exhibited by fluorite, nearly all specimens
of which will, when gently heated, emit a visible light. The color
of the light varies with different varieties, and is usually not the same
as the natural color of the mineral. The tints exhibited are usually
greenish, bluish, or purplish. On increased heating the phosphorescence
disappears, and cannot be restored again except by passing an electric
discharge through the mineral, whereupon the lost power is usually
regained. The same is true of diamond. It is generally supposed
that the phosphorescence of minerals results from the presence within
them of particles of organic matter of the nature of hydrocarbons,
which are aroused to a certain activity on heating. Of the exact
nature of the phenomenon, however, little further is known.
Closely allied to phosphorescence is fluorescence, which, in a strict
sense, is the emission of light within a substance while it is being
exposed to light, or in some cases to an electrical discharge from
a vacuum tube. Fluorite is again the mineral which best exhibits
this property, a beam of white light passing through a colorless cube
of it producing a delicate violet color. The diamond, ruby, and other
gems are stated by Dana to give forth
a brilliant fluorescence when exposed to an
electrical discharge from the negative pole
of a vacuum tube. Fluorescence is also pro-
duced in the diamond by radio-active sub-
stances; that is, by radium, or substances
possessing its activity. In this respect dia-
mond differs from such gem minerals as
ruby, emerald, topaz, etc., and from glass,
in none of which do the radium rays excite
much activity. X-ray photograph of paste and
The behavior of gems toward X-rays or ^idn taring a? *&, to
n rays Varies with different species, opaque; the real diamonds, in the
, , j. , . . . . , . ring at the right, transparent.
and artords a means ot distinguishing them.
Thus diamond is quite transparent to the rays, while glass is opaque.
Accordingly, in an X-ray photograph, such as is shown in the accom-
panying figure, of two rings, the one set with diamonds, the other with
paste, the diamond can readily be known by its transparency.
The behavior of others of the gem minerals in relation to the X-rays
is further shown in the following table :
The crystal form of minerals serves as an important means of identi-
fying them, since crystals of each species, in any system, except the
isometric, have forms peculiar to that species. The actual determi-
nation of species in this way, however, requires a careful measurement
of angles, trigonometrical calculations, and a knowledge of crystal forms
obtained through a study of that branch of mineralogy known as crystal-
lography. The mastery of this subject is usually beyond the purpose
of the student of gems, nor is it essential. A more practical need
Distortion of a cubical crystal by variations in growth
for him is to obtain a certain empirical familiarity with the common
external forms of the crystals of each species, together with a knowl-
edge of the ways in which distortion may occur, preventing recognition
of the regular forms.
In the following pages, under most of the species, are given illus-
trations of the common forms of those species, which one soon learns
to associate with that particular mineral.
In all comparisons of figures with actual crystals, however, it must
be remembered that crystals in nature rarely present the complete,
symmetrical form which the geometrical figure would indicate. While
the angles between the faces remain practically always the same, there
occur much distortion and imperfect growth of crystals which may
be quite misleading. Certain faces may be so much developed that
others which would normally be present, do not appear at all; and
again, the attachment of the crystal to its matrix often prevents develop-
ment of the complete form, or obscures its presence.
Thus in the above figure the cube, which would be the normal crystal
form, may become by continued growth in the vertical direction elon-
gated like the form shown at its right, or by growth laterally the tabular
form shown may be produced.
So again, the quartz crystals represented below are all made up of
the same faces and have the same interfacial angles, yet they would seem
Forms of quartz crystals produced by distortion
at first sight to have no similarity of form. One can soon become famil-
iar with these variations, however, and by making due allowance for
them learn to recognize crystal forms quickly and accurately.
In addition to an empirical familiarity with the forms of crystals,
some knowledge of the general groups of crys-
tals is desirable, since there are thus expressed
relations which characterize not only the ex-
ternal form, but internal structure.
The forms into which a mineral, or any
substance of definite chemical composition,
may crystallize, are divided into six systems.
These are known as the isometric, tetragonal,
hexagonal, orthorhombic, monoclinic, and tri-
clinic systems. By some a seventh, called the
rhombohedral system, is added, though here it
is considered a subdivision of the hexagonal.
In the discrimination of crystal forms, the
relations of the planes can best be expressed
by referring them to a series of three or more
imaginary axes within the crystal. One of
these, known as a, is supposed to run from
front to back ; another, known as 6, from Crystal Axes
right to left ; and the third, known as c, vertically The latter is known
as the vertical axis, and the two former are designated as lateral axes.
In the hexagonal system, the existence of three lateral axes is assumed.
The differences between the six systems can be stated in terms of
these axes as follows:
In the isometric system the axes are of equal length, and at right
angles to each other. In the tetragonal system one axis, usually taken
as the vertical, is longer or shorter than the other two, which are equal
in length. The axes are all at right angles to each other, however. In
the hexagonal system one axis, usually taken as the vertical, is longer
or shorter than the lateral axes and at right angles to them. The
lateral axes are three in number, of equal length, and meet at angles
of 60. In the orthorhombic system the three axes are of unequal
length, but meet at right angles. In the monoclinic system the three
axes are of unequal length. Two of them meet at right angles, while
the third is inclined. In the triclinic system the axes
are of unequal length, and meet at unequal angles.
The axial relations above class-
ified are paralleled in the symmetry,
and internal, of
Crystals. Thus Octahedron
crystals of the
isometric system are the most highly Dodec ^edron
symmetrical, and those of the tri-
clinic system the least so. By symmetry is here Trapezohedron
understood the relation which an object has to its
reflection in a mirror ; and another way of stating the previous obser-
vation would be to say that an isometric crystal can be held before
a mirror in more positions in which the crystal and its reflection
present the same appearance, than one of any other system, while with
a triclinic crystal no such position can be found. Besides the division
into six systems, each system is itself subdivided into groups of varying
kinds of symmetry. There are thirty-two of these groups, characterized
by a particular kind of symmetry, and a substance crystallizing in a
certain group will invariably show that symmetry.
A few simple forms peculiar to different systems may be mentioned
here, since the terms will be often employed in the text. Four common
forms, exhibited by minerals crystallizing in the isometric system, are
the cube, octahedron, dodecahedron, and trapezohedron. The cube is
a solid bounded by six similar faces, each parallel to two of the axes.
Each face is a square, and the interfacial angles are all 90. Crystals
of this form are exhibited by pyrite, fluorspar, and rarely by diamond.
The octahedron is bounded by eight similar faces, meeting the axes
Tetragonal prism and
at equal distances. Each face is an equilateral triangle. Diamond and
spinel are gem minerals which often exhibit crystals of this form.
The dodecahedron is bounded by twelve faces, each of which meets
two of the axes at equal distances, and is parallel to a third axis.
Each face is a rhomb. Garnet quite commonly crystallizes in this form,
as well as in that of the next type, the trapezo-
hedron. The trapezohedron is bounded by
twenty-four faces, each of which is a trapezium.
Each face intersects one axis at the unit length,
and meets the other two axes at distances
greater than unity. The form bears some rela-
tion in appearance to the octahedron, if it be
imagined that three faces of the trapezohedron
occupy the place of one face of the octahedron.
In other systems than the isometric, the
simplest and in general the most commonly occurring forms are prisms
and pyramids. Prisms are forms whose faces are parallel to the vertical
axis, while they meet the lateral ones; pyramids are forms whose
planes meet all three of the axes.
In the hexagonal system prismatic and pyramidal faces occur in
multiples of three, while in the tetragonal, orthorhombic, etc., systems,
they occur in multiples of two. Thus a crystal of zircon
may be distinguished from one of quartz, for example, by
the fact that on the former four or eight similar pris-
matic faces may be counted, on the latter, three or six.
Substances vary considerably in their tendency to form
distinct crystals, or even to crystallize. Quartz, in the
form of rock crystal and amethyst, is generally found in
distinct crystals, while agate, chalcedony, etc., although
crystalline, and of the same composition, never form
separate crystals. . Such substances as opal, turquois,
obsidian, and obviously those of organic origin, such as amber, jet,
pearl, and coral, never crystallize, or possess regular external form.
Such substances are termed amorphous. As a rule, gem minerals are
those tending to occur in distinct crystals, since crystallization usually
favors transparency and purity of substance.
CUTTING AND MOUNTING
The condition in which gems are found in nature is rarely such
as, according to the general notion of human kind, exhibits their
greatest beauty. In the state of nature, the surfaces of gems are gen-
erally dull and lusterless ; their shape is irregular, and their mass is per-
meated by flaws and imperfections. Moreover, the powers of reflection
and refraction of light, which give gems their superior brilliancy and
fire, can only be brought out in perfection when the stones are shaped
with reference to their internal structure. Hence, from the earliest
times, man has endeavored to increase the beauty of gems by bring-
ing them to a condition of the highest possible polish and luster.
The progress of this art has been a gradual and slow one; but in
its present development it affords an opportunity for. the exercise
of knowledge and skill of a high order. It is true that from time to
time certain art critics, among whom was Ruskin, have urged that gems
in their native state are more beautiful than when cut, but such views
overlook the obvious enhancing of the optical qualities of a gem by a proper
cutting. The mere facetting of a stone may be, as these critics claim,
an expression of a somewhat vulgar taste ; but cutting a stone with
reference to its optical structure applies an intelligent skill which can
but prove enhancing to its natural beauty. Occasionally a diamond
or ruby crystal is found of sufficient regularity of form and purity
to make it available in its natural state for use as a gem ; but ordinarily
the art of the lapidary is needed to bring from precious stones an exhi-
bition of their full beauties, and fit them for the highest purposes of
ornament. On the other hand, there is a common notion as to the
amount of improvement that can be made in a stone by cutting or
facetting, which is generally a mistaken one. There is no stone so dull
and lusterless that some one will not think that it would be beautiful if
it could only be cut and polished. But as a matter of fact, cutting or
polishing usually changes the appearance of a stone very little, and a
stone which is not attractive in color and transparency before cutting is
not likely to be after. The skilled lapidary, it is true, can select the
most favorable parts of a mass for cutting, but more than this he cannot
do; and much disappointment may be avoided if only those stones are
cut which can be seen while in the rough to have the necessary desir-
The first effort on the part of man to improve upon the natural
appearance of gems was confined to giving them a simple polish.
At first only the natural surfaces were polished, but later the rough
corners were rounded, and gradually the plan of giving them a symmet-
rical shape developed. To this day, however, the treatment of gems
A Ceylonese gem cutter of the present day
in the Orient is confined largely to rounding and polishing the stones,
with little alteration of their natural shape. The Kohinoor diamond
in the form in which it reached England is an illustration of the
unsymmetrical shape which is allowed by Orientals to be retained
by even their most costly gems. The appliances by which this work
of polishing and cutting gems is still performed in the East are of the
crudest kind, and show little advancement from the earliest types used.
The accompanying cut shows how a Ceylonese gem-cutter of the pres-
ent day plies his trade. His wheel is supported on two upright pegs
set in the floor timbers of his house. A wooden axle, on the end
of which is the disk for polishing, is inserted in these. The axle,
and thus the disk, is rotated by pushing back and forth upon it with
the right hand a long stick to which is fastened a string passing once
around the axle. The stone to be polished is held against this revolv-
ing disk by the left hand, either with the fingers directly, or by a stick
to which the stone has been cemented. Abrasive powders and water
are contained in bowls made by sawing cocoanut shells in two, and
the abrasive is applied to the wheel by dipping the stone at intervals
into the mixture. By this painfully slow and laborious process the
polishing of the gem is in time accomplished.
Among Occidental peoples, the cutting of gems was early carried
to a much higher point than among Orientals. By both Greeks and
Romans gems were given a symmetrical form, and they carried to
a high degree of perfection the art of cutting cameos and intaglios
The different forms into which precious stones are cut at the pres-
ent time may be arranged in two groups: (1), those having plane sur-
faces; and (2), those having curved surfaces, although the two may
be combined in the same cutting. The different forms under these
subdivisions may be grouped, following Church, thus:
1. Plane surface cuttings - - - -
Step or Trap.
Mixed or Brilliant Top.
( Single cabochon.
2. Curved surface cuttings - - - - -s TT
I Tallow top.
Of these cuttings, those of the first group are usually used for
transparent stones, such as the diamond, emerald, and ruby; and those
of the second for translucent and opaque gems, such as the opal,
turquois, moonstone, cat's -eye, and the like. The garnet is cut in
both ways, the cabochon-cut garnet being called a carbuncle.
The question as to which form of cutting should be used for any
particular gem is one involving considerations of the mineral species
and the peculiarities of each individual stone. On the one hand, it
is desirable to avoid as little loss of the stone as possible; and on the
other, to give it that shape and proportion which shall best bring out
its luster, brilliancy, and color. Pale stones should, for instance,
have greater depth than dark ones; the latter should be given more
" spread" and less depth. A well -cut stone is worth considerably
more than a poorly cut one, even if the latter has a greater weight.
Often in cutting a stone one-half and even more of its mass may
be removed, and yet the stone be improved thereby. The brilliancy
of a stone is increased, other things being equal, the larger the num-
ber of facets which can be given it. The value of the stone must be
taken into consideration in this connection, however. Stones of mod-
erate value do not have their worth sufficiently increased by addition
of numerous facets to warrant the expenditure of the extra time and
labor that would be required to bring them to this condition. If a stone
is strongly dichroic, as is iolite for example, the cutting must be in
Side view of brilliant
Brilliant seen from
above. SK, skill facets ;
QU, quoins or lozenges ;
ST, star facets; CR,
cross or skew facets;
TEMP, templets or bezils
Brilliant seen from be-
low. SK, skill facets ;
CR, cross facets
such a direction as to bring out this quality in the highest degree.
Similarly tourmaline, because of its dichroic properties, may make
a dark and uninteresting stone if cut at right angles to the crystal-
lographic axis, while if cut parallel to this axis it will make a bril-
liant appearance and show two colors. Such stones as moonstone,
labradorite, tiger's-eye, and others, which show chatoyancy only in
certain directions, must obviously be cut with reference to this fea-
ture. In transparent stones, the angle which the upper and lower
facets make with each other should be a definite one, so as to reflect
the light in the best possible manner.
Considering briefly and in order the forms of cutting above men-
tioned, we may note first the brilliant. The brilliant cut is said to have
been invented by Cardinal Mazarin in his endeavors to introduce the art
of diamond-cutting into France. It is now the form most commonly given
diamonds and is employed for many other transparent stones as well.
As will be seen from the above figure, it is made up essentially of
two truncated pyramids joined by their bases, the upper pyramid
leaving one -third and the lower pyramid two -thirds of the length
of the stone. The upper pyramid is called the crown, the lower the
pavilion. The plane on which they join, and which represents the
greatest breadth of the stone, is the girdle. The flat top of the upper
pyramid is known as the table. It should be four-ninths of the breadth
of the stone. . The corresponding termination of the lower pyramid is
known as the culet, and this should have an area one-sixth to one-fifth
of that of the table. The number of facets given these pyramids
varies with different cuttings; but the typical has fifty-eight, which
have individual names, as indicated in the diagram.
The outline of the brilliant cut is not always so nearly circular
as in the form shown in the diagram, although this is usual. Brilliants
are sometimes cut so as to have a nearly square
outline, or again they may be made triangular,
or again oval.
The proportions of the brilliant above given
are not always followed by lapidaries, if it is
deemed that they would involve the loss of too
much material, or if the cutter believes it possible
to improve the effect of the stone by depart-
ing from them. The former consideration has
weighed most largely in the cutting of some cele-
brated diamonds, with the result that according
to some critics the stones do not show to the best
Trap or step cut as seen T rrn J.T IT- i T i -
from above and below advantage. Ihus the Kohmoor diamond in its
present form is said to be too broad for its depth,
and the Regent too thick for its breadth.
The second cutting to be noted is the trap or step cut. This is a
favorite form of cutting for colored stones. It is a shallower cutting
than the brilliant, and has a broader table. The outline is commonly
oblong, in contrast to the more nearly circular form of the brilliant, al-
though quadrilateral, hexagonal, and other outlines may be given. The
rules of proportion are far less strict than those applied to the brilliant.
The following form is a common one, however : Beginning with the table
above, two sloping or step facets lead to the girdle, below which three to
five or more sets, or zones of diminishing steps, extend to the culet. The
latter has the general shape of the stone. The number of the facets is often
increased over the above with advantage. A common fault with the
step cut comes from making the table too broad, since the internal
reflections from the lower facets are best seen, as Church states, through
the sloping bezils of the crown, not through the flat surface of the table.
The mixed or brilliant top cut is a combination of the brilliant and
Top and side views of
The table cut is a simpler cutting than either the step or brilliant.
It consists simply of a table with beveled edges. It is an old form
of cutting, and is generally superseded at the present day by forms
with a greater number of facets.
The rose cut has the crown facetted all over,
the table of the brilliant being replaced by six
triangular facets, and the other facets by eighteen
triangular ones. The base is either made flat, or
as a duplicate of the upper part, the latter cut
giving what is known as the " double brilliant."
The rose cut is especially useful for small or
flat diamonds, as by means of it well-cut gems
can be made from pieces of " rough " which are
too small or too thin to make brilliants.
Besides the brilliant and rose, which are stan-
dard cuttings for the diamond, there are several quaint and fanciful
cuts which are now more or less in vogue. One of these is the
" pendeloque," a sort of double rose cut, and the " briolette," also a
double rose cut of a general pear
shape. The outline of the stone
may be varied also, so as to be tri-
angular, hexagonal, or circular. A
form of diamond cutting which is
now being extensively advertised is
that called the " twentieth century "
cutting. This is a double rose cut
with eighty planes, forty above and forty below. It
is made up essentially of two cones placed base to
base, both completely facetted with planes, eight of
which meet around each apex. The supposed supe-
riority over the brilliant rests in the substitution of
facets for the table and culet of the latter.
The curved cuttings given to precious stones are
all modifications of the form known as cabochon, the
various shapes given being such as are best adapted
to bring out the beauties of the individual stone
which is to be cut. The different forms of the
cabochon can be sufficiently well understood by refer-
ence to the accompanying figures. The hollow cabo-
chon serves the purpose of lightening the color of
dark stones, and affording a place for inserting a foil.
Flat or tallow-top
The manner in which the actual work of cutting and polishing
gems is performed by the most advanced methods of the present day
varies somewhat with the kind of stone. Some stones naturally require
a much harder abrasive than others, while different wheels and differ-
ent polishing powders are suited to different gems. In general, the
stone is reduced as nearly as possible to the desired shape by careful
cleaving in the rough. If there is a natural cleavage much use can
be made of this in bringing the stone to the desired shape ; if not,
the work cannot be carried far in this manner. Large stones, if not
too hard, can be sawed to a desirable shape with diamond or carbor-
undum saws. After having been shaped as nearly as possible by one
of these methods, the rough stone is then soldered to a metal handle,
or cemented to a stick by means of wax or other adhesive substance,
and ground to a rounded symmetrical shape on a flat, revolving wheel,
the abrasive used being applied by means of water or oil. The wheels
used are generally either of iron or copper, though lead, tin, and even
wooden wheels are employed. For all gems except the diamond, the
cutting of which can be carried on only by means of diamond dust,
emery or ground corundum is the abrasive generally used,, although
since the invention of carborundum this is employed quite extensively.
After the stone has received a general rounding in this manner, the
cutting of facets, one at a time, is begun. To maintain the exact
I angle at which each facet is to be cut, a clamp is provided above the
wheel, in which is fastened the handle on which the gem is soldered.
By this means the stone is held against the wheel at the desired
angle until the facet is cut. For facetting cheap stones the handle
of the gem is sometimes held in the hand; but while the work
can be done faster by this means it obviously cannot be performed
so accurately. After the stone has received by grinding the proper
number of facets, each of the size desired, the work of polishing must
be performed. This is done in a similar way to the grinding, except
that softer abrasives and softer wheels are used. Rouge, tripoli, and
" putty powder " are the abrasives most commonly used for this pur-
pose, they being applied dry or moist to wheels of leather, felt, or paper,
against which the stone to be polished is held.
Owing to its superlative hardness the cutting of the diamond must
be performed by a somewhat different process than that of other stones.
The facets upon a diamond are cut by rubbing together by hand two
diamonds cemented upon sticks. After the facets have been outlined
in this way they are ground and polished upon wheels to which diamond
dust is applied, in a manner similar to that described for other gems.
The grinding and polishing of agates and other large stones are
performed at Oberstein, Germany, on an extensive scale, in mills
fitted up in the manner indicated in the accompanying cut. The
wheels for grinding turn vertically instead of horizontally as is usually
the arrangement when cutting small stones. They are made of sand-
stone, are about five feet in diameter, and often a foot in thickness.
Their edges are often fluted in different shapes, so as to give different
Agate cutting at Oberstein, Germany. After Bauer
desired forms. The piece to be cut is held by the workman by hand
against the wheel until it has received the desired shape. After being
ground it is polished on a wheel of hardwood with tripoli, this part of
the work being usually performed by women and children.
After a gem has been cut, the question of its proper mounting and
setting must next be considered. While some gems are worn unmounted,
as for instance the pearls of a necklace, the great majority are set in
metal. This work is the especial art of the goldsmith or jeweler, and
the laity usually take little pains to be informed in regard to it.
There is room, however, for the development of a much higher taste
in these matters than exists at present. The average buyer is con-
tent to know that the article which he purchases contains a sapphire,
emerald, or diamond, representing so much intrinsic value, without
considering whether the best use of it, from an artistic point of view,
has been made; or whether for the same outlay much more pleasing
effects might not have been obtained from other stones. In the group-
ing of gems, with regard to effects of color, luster, texture, etc., certain
combinations often seen are far from ideal, while others rarely seen
would be admirable. Thus a combination of the diamond and turquois
is not a proper one, since the opacity of the latter stone deadens the lus-
ter of the former. The cat's-eye and diamond make a better combination,
and so do the more familiar diamond and pearl. Colorless stones, such
as the diamond or topaz, associate well with deep-colored ones, such as
amethyst and tourmaline, each serving to give light and tone to the
other. Diamond and opal as a rule detract from each other when in
combination, since each depends upon " fire " for its attractiveness.
Methods of mounting gems may be described as being essentially
two in number, one the mount a jour, and the other the encased
mount. The mount a jour, so called from two French words mean-
ing to the light, is illustrated in the well -known manner of setting
ring stones, by which the stone is held in place by a circlet of claws,
exposing it to view on all sides. This mounting is especially suited
to colorless and transparent stones without flaws, as it allows the
freest play of light upon them, and permits their beauties to be fully
seen. Jewels set in this way are, however, in greater danger of being
lost, since the gem cannot be quite as firmly held as in the encased
mount. In the encased mount the stone is set in a metal bed with
only the top exposed. This mount is familiarly seen in many articles
of jewelry. Being cemented to the metal bed the stone is in less
danger of loss or injury than in the mount a jour. With the encased
mount the effect of the stone can be much enhanced by the use of foils
and paints, and many defects can be made invisible. Thus black specks
in a stone can be overcome by setting against a black background,
while a gold foil serves to bring out the fire of a garnet, for example,
as an a jour setting could not. In all this work of setting gems and
overcoming their defects, the Oriental peoples especially excel, and
have done so for centuries. Examples of their work furnish, as a
rule, the best models for study.
VALUATION AND PRICE
The unit of valuation by weight of gems in most countries is the
carat. This term meant originally, according to some authorities, the
weight of a bean of the coral tree (Ery 'thrina), known in Africa as kuara,
and used there for weighing gold-dust. Others believe the term to be
derived from the Greek word keration, said to be the name of the
fruit of a variety of acacia having seeds of remarkably uniform size.
As at present employed the weight of the carat expressed in grams
is about one-fifth of a gram (200 milligrams), but varies in different
countries from 197 to 216 milligrams. Th'e accepted weight in most
of the large gem markets, such as Paris, London, and Berlin, varies
little from 205 milligrams. This makes a carat weight a little over 3
grains troy, the exact decimal being 3.165. Hence one grain troy =0.3 16
carat, and one ounce troy=151.7 carats. The weight of the carat is
usually given as four grains troy, but this is obviously not quite correct.
The carat is subdivided into four equal parts, also known as grains, which
evidently have not quite the weight of the troy grain, although the two
are often confounded. The balances used for weighing gems are usually
divided into sixty-fourths, and the fractional parts of a carat weight are
then expressed by series of common fractions rather than by one fraction
or a decimal. Thus a gem weighing 3|f carats might have its weight
expressed in this manner, 3^, ^, ^. This is a record of the succes-
sive divisions of the scale met in making the weight, not reduced to
a simple fraction.
The size of a stone of a given number of carats obviously varies with
specific gravity of the gem; a two-carat sapphire, for instance, being a
smaller stone than an emerald of the same weight. The size of diamonds
of different carats weight is shown by the accompanying cuts, and they
represent approximately the size of most gems of the same number of
The size of a stone, besides being indicated by weight, is frequently
expressed by a number. This number refers to a scale of standard sizes
adopted by jewelers, which runs from 1 to 50. Thus a stone of the size
of No. 12 in the scale has a weight of one-eighth of a carat, No. 24 one-
half a carat, No. 38 two carats, and so on. The scale thus affords a
means of distinguishing smaller differences of size than would be con-
venient by weight alone.
The measurement of the weight of pearls differs from that of other
gems in that pearls are measured by their weight in grains. The grain
here employed is not the troy grain, however, but four-fifths of it, so
that four troy grains are equal to five pearl grains, and a troy ounce
contains 600 pearl grains.
So far as the more precious gems are concerned, it may be noted that
their price increases in a much higher proportion than does the weight.
According to a rule, sometimes called Tavernier's and sometimes Jeffries'
rule, the price should increase as the square of the weight. Thus if a
Exact sizes of diamond brilliants from 34 to 100 carats weight
carat stone is worth $80, a five-carat stone would be worth not five
times $80=$400, but 5 2 or 25 times $80=$2,000. The rule, how-
ever, affords no more than an approximation of the value, it giving in
general too high a result. Some gems, such as amethyst, topaz, and
others, increase in value only in about the same proportion as they increase
in weight, since large stones of these species can be readily obtained.
In addition to weight, quality is a factor largely affecting the price of
precious stones. To be of the first quality, or first water, a gem must be
of uniform luster and color, must be free from cracks of every kind, from
bubbles, and if transparent, from inclusions of every sort, cloudy spots
or streaks. Any of these flaws can usually be distinguished by holding
the stone between the eye and the light, or they are more clearly brought
out if the stone is immersed in a liquid with high refractive power, such
as oil of cloves, linseed oil, or even kerosene. These flaws may occur in
the rough stone, or the operation of cutting may produce little cracks,
called feathers, which injure the value. Obviously, therefore, to be sure
of obtaining a flawless gem, it should be purchased after the operation
of cutting has been completed.
The value of rough stones compared with those cut varies with the
variety and size of the stones. Not only does cutting reduce the stone in
size, but the cost of cutting must be taken into consideration. The latter
may represent almost the entire value of stones the raw material of
which is abundant and cheap, as is true of many of the varieties of
quartz. In the case of diamonds the cost of cutting adds about 50$> to
The price of gems, besides varying with quality and species, is de-
pendent like that of other commodities upon supply and demand, which
are in turn affected by discoveries of new sources, and by changes of
fashion. Thus the discoveries of diamonds in Brazil and South Africa
respectively caused a fall in the prices of this gem at each of these
periods because of the increased supply afforded. In 1750, just before
the influx of Brazilian diamonds into Europe, one-carat stones were
valued at $40. Shortly after, when the supply from Brazil poured into
the market, they fell to a value of only $5. In 1791 this price had
risen to $30. This fell again to $20 during the French wars of 1848, but
by 1865 had risen to nearly $100, which is not far from the present price.
At the present time the emerald has reached an unprecedented price,
because while the demand is steady the supply has almost entirely failed.
On the other hand, the sapphire has fallen about 25$ in value in the last
twenty years on account of the discovery of new fields. In some cases,
however, the failure of supply of a little-used gem may cause the
demand for it to cease, as has happened with the Italian diopside.
The price of the four gems, diamond, ruby, sapphire, and emerald, is
on the whole little influenced by changes of fashion, for they seem to
be always in demand. Most of the other gems, however, vary in price
with the fashion, being at one time much in vogue and again almost for-
gotten. Thus topaz is now little prized, but Kunz states that the mines
of this gem in Spain have been bought and are being held by a French
company in anticipation of a return of the stone to fashion. This might
cause a demand for it equal to that of forty years ago, when it brought
from $4 to $8 per carat.
As gems are objects of luxury, and not of necessity, the demand for
them is greater, and hence their price is higher, in times of prosperity.
Vice versa in hard times, or periods of financial depression, prices of
gems fall. The period following the French Revolution witnessed a great
lowering of the prices of gems, partly because the previous extrava-
gances of the French court in this direction had been one of the sources
of popular discontent, and partly because of the general financial depres-
sion. At the present time in the United States the magnitude of the
gem trade is greater than ever before.
The skill with which a stone is cut should be taken into considera-
tion in valuing it, although this is a matter upon which only an expert
is competent to give an opinion. Of two stones of the same weight
and equal quality, one may be worth ten times as much as the other
because more skilfully cut. Further, the exact qualities desirable in
any particular gem are points to be learned by long skill and experience,
and stones possessing these qualities command much higher prices
than the ordinary.
IMITATION GEMS AND HOW TO
The art of imitating gems has reached a high degree of perfection,
and while the substitutes thus prepared have legitimate uses, the tempta-
tion to palm them off on the unsuspecting for real gems, at or near
the price of the genuine, is often too strong to be resisted. It becomes
important, therefore, that every one purchasing precious stones should
be acquainted with the characteristics of the false as well as of the
real, and unless purchasing of a perfectly reliable dealer should sub-
ject the offered stone to the most careful scrutiny. Tourists are espe-
cially liable to deception of this sort, since their purchases must be
largely made of itinerant venders, with whom they are not acquainted.
The Persian turquois venders, knowing the liability of some of their
wares to fade, are accustomed to leave for parts unknown as soon
as their stock is disposed of, and gem-sellers of other nations often
exhibit similar propensities.
Emanuel tells of a man who left his business in his own country,
and at considerable expense went to England to sell a quantity of stones
which he had been assured were diamonds, only to find on arrival there
that they were simply quartz. This experience in one form or another
has doubtless been repeated countless times, and should serve to show
the importance of knowledge on the part of all purchasers of gems of the
features which make them intrinsically valuable.
It may be said in general that the one quality of most gems which
cannot be successfully duplicated is their hardness. The best simple
protection therefore against purchase of a glass imitation for most precious
stones will be found in a test of this property. Glass is softer than
most precious stones, and hence is much more easily scratched than
they. It will yield to the file, while they will not. This test should
of course be made so as to avoid injury of the stone, for often the
girdle of a gem cut as a brilliant is as delicate as a knife edge, and
great care should be used in testing it. If a file be not convenient,
a fragment of quartz can usually be obtained, and affords an accurate
means of testing hardness, since the hardness of quartz is 7, and that
of glass rarely over 5. An aluminum pencil also affords a safe means
of testing hardness. Drawn over glass it leaves a white, silvery line,
but on hard gems little if any mark. In respect to color, luster, and
even specific gravity, glass may be made to imitate almost any gem.
Even natural looking flaws can be made in a glass imitation by dexter-
ous hammer blows. Nevertheless glass can often, though not always,
be distinguished from a mineral by the fact that in a piece of glass
minute air bubbles may be seen on examining it with a lens. These
bubbles generally differ in shape and number from any found in natural
minerals. Glass also has a characteristic conchoidal fracture not quite
like that usual to minerals. Jj'ue gems are colder to the touch than
glass as a rule, although glass is colder than such substances as jet,
amber, and pearl, for which it is often substituted. The^colder feeling
of true gems comes from their being better conductors of heat than glass,
so that they take away warmth from the hand more rapidly. For the
same reason most true gems when breathed upon acquire a thicker coat-,
ing of moisture than glass and lose it more quickly than does that sub-
stance. In the application of these simple tests jewelers often become
very skilful, and if the stones are not too small can pick out a diamond,
sapphire, or other gem from a whole bagful of glass imitations by the
above distinctions alone. When in the rough, a useful distinction of
glass from most gems is to be found in the easy fusibility of the former
before the blowpipe. While most gems are practically infusible in this
way, glass is easily fused, and hence the trial of a splinter of the sub-
stance before the blowpipe affords a test of value. The distinction of
glass from minerals by an observation of their behavior in polarized light
can be made without injury to the substance tested, and with reliable
results. To be sure, the distinction of glass from diamond, spinel-ruby,
or other singly refracting gem, cannot be made in this way ; but when
the stone is doubly refracting, as is the case with the majority of species,
such investigation affords one of the surest and most convenient means
of identification. The use of the dichroscope or polarizing microscope
for this purpose has already been explained.
The glass used for making imitation gems is usually one having a
high percentage of lead in its composition. The lead makes it soft but
gives it great brilliancy. The glass is usually known as paste, or strass,
the latter name being from the inventor, Strass of Strassburg, who
invented the mixture during the seventeenth century. Uncolored it
affords a good imitation of the diamond, and when colored with various
metallic oxides, remarkably accurate likenesses of different gems can be
Besides counterfeits wholly of glass, many precious stones are adul-
terated, so to speak, by making a portion of a genuine stone, and
employing glass for the remainder. Such fabrications are called
doublets, the upper part of the stone being of course the genuine
portion. The application of a file to the upper and lower parts in
turn will usually detect the fraud; or if the two parts are cemented
together by gum mastic, as is usually done, they will separate on
being soaked in warm water. The union can also often be seen on
holding the cemented stone up to the light. Occasionally, however,
the two are fused together, in which case soaking would not separate
them, nor would the plane of union be visible. A desired color is some-
times given to doublets by inserting a foil between the two portions.
Besides the use of glass in place of precious stones, an effort is
often made to substitute a cheaper stone for the one represented.
Quartz, white sapphire, and topaz may thus be substituted for diamond,
pink topaz for ruby, and so on. In such cases the distinction of hard-
ness is not as marked as if glass is employed; but the test with light
can usually be made, and determination of the specific gravity, or other
property, often serves to detect the counterfeit.
Besides employing the above-named devices, deception is sometimes
achieved by making a large stone of two smaller ones of the same
mineral cemented together. Again, inferior stones may have their backs
painted to give them a desired color. The practice of setting a stone
against a foil in order better to bring out its color or luster as, for
instance, mounting an opal or moonstone on black, or garnet against
silver is not considered illegitimate, and should by all means be
employed when the effect of a stone can thus be enhanced.
The difficulties of detecting fraudulent gems will obviously be greatly
increased if the stones are set. Gems should, therefore, always be pur-
chased loose if possible, especially costly ones.
On the whole, the accurate distinction of gems, or detection of frauds,
requires knowledge of the different physical characters of each species,
such as hardness, specific gravity, and behavior in polarized light.
A single test is rarely sufficient to identify a gem; but by the use
of several, perfectly trustworthy results can be obtained.
SUPERSTITIONS REGARDING GEMS
From the earliest times and among all peoples there seem to have
been sentiments and superstitions connected with gems. Not only
was the power of driving away evil spirits and producing all sorts
of " luck " long attributed to them v but as late as the beginning
of the eighteenth century reputable physicians were accustomed to mix
fragments of them in their medicines and to use them as charms. /To
this day amber is kept in stock by druggists in Paris for use in filling
prescriptions. xThe Chinese still use powdered pearls, coral, and other
gems in medicine, and various Indian tribes of North America ascribe
great medicinal value to one gem or another. In the writings of Greek
and Roman writers are found many statements indicating belief in
the medicinal and other virtues of gems. It was in the Middle Ages,
however, that these opinions seem to have been most widely and firmly
held, so far as it is possible to learn of them through history.
The following passage from Marbodus, a writer of the latter part
of the eleventh century, is a good example of some of the virtues
attributed to gems in that time:*
"The chalcedony, if blest and tied round the neck, cures lunatics.
Moreover, he that wears it will never be drowned or tempest-tossed.
It also makes the wearer beautiful, faithful, strong, and successful in
all things. One ought to engrave upon it Mars armed, and a virgin
robed, wrapped ha a vestment, and holding a laurel branch; with a per-
'Aristotle, in his book on gems, says that an ^emerald hung from
the neck, or worn on the finger, protects against danger of the falling
sickness. We therefore commend noblemen, that it be hanged about
the necks of their children that they fall not into this complaint.
The emerald is approved in all kinds of divination; in every busi-
ness if worn it increases its owner's importance, both in presence and
"A sard, of the weight of twenty grains of barley, if hung round
the neck or worn on the finger, the wearer shall not have terrible
* King, Antique Gems, p. 432.
or disagreeable dreams, and shall have no fear of incantations or
"The beryl is a large and transparent stone. Engrave upon it
a lobster, and under its legs a raven, and put under the gem a vervain
leaf, inclosed in a little plate of gold; it being consecrated and worn,
makes the wearer conqueror of all bad things, and gives protection
against all diseases of the eyes. And if you put this stone in water,
and give this water to one to drink, it cures stoppage of the breath
and hiccups, and dispels pains of the liver. It is useful to be worn, and
he that hath this gem upon him shall be victorious in battle over all his
foes. It is found in India, like unto the emerald, but of a paler cast.
"The sard is good to be worn, and makes the person beloved by
women; engrave upon it a vine and ivy twining round it.
"The casteis (callais turquois) is good for liberty, for he that hath
consecrated it, and duly performed all things necessary to be done in
it, shall obtain liberty. It is fitting to perfect the stone when you have
got it, in this manner : Engrave upon it a beetle, then a man standing
under it; afterwards let it be bored through its length and set on
a gold fibula (swivel); then being blest and set in an adorned and
prepared place, it will show forth the glory which God hath given it."
Some of the other traditional virtues of gems ascribed chiefly in
the Middle Ages, but many doubtless of earlier origin, are as follows :
Agate was believed to have the power of averting storms, counter-
acting poison, and stemming the flow of blood. A black agate with
white veins was considered a potent talisman against every danger,
and to have the power of rendering the wearer invisible.
Amber worn in beads about the neck or wrist was regarded a cure
for sore throat and ague, and a preventive of insanity, asthma, dropsy,
toothache, and deafness.
The bloodstone prevented death from bleeding.
The cat's-eye warned its wearer of danger, storms, and troubles,
and was a charm against witchcraft. It was also a cure for croup when
Precious coral prevented blight, caterpillars, storms, and locusts,
and was a charm against lightning, whirlwind, shipwreck, and fire.
Taken internally it was a cure for indigestion.
The diamond was a talisman against danger, and gave hardiness,
fortitude, and manhood to its owner.
The emerald gave immortality, won the favor of rulers and paci-
fication of enemies. If its wearer was unmarried it rendered him
The garnet was a preventive of fever and dropsy, and rendered
its wearer agreeable, powerful, and victorious.
The hyacinth gave second sight, promoted sleep, and preserved
from thunderstorms and pestilences.
lolite foretold storms by changing hue.
Jasper had the power of stopping overflowing blood, or water, and
was a preventive of poison.
Jet induced fertility.
Moonstone was believed to contain an image of the moon, which
grew clear upon days and occasions fortunate to its owner, and dim
with the reverse. It was thought to wax and wane with the moon
and was a cure for epilepsy.
The onyx exposed its wearer to lawsuits, bad dreams, and demons.
If a sard were worn with it, however, these evil influences were counter-
acted. It symbolized and insured conjugal felicity.
The opal faded upon the insincere, deceitful, and impure ; but when
worn by the innocent united the special virtues of all gems.
The pearl insured entrance to Heaven; but this privilege might
be lost by carelessness of life.
Quartz if burned averted storms, and powdered and mixed with
water cured serpents' bites.
The ruby preserved its owner's house or vineyard from lightning,
tempest, and worms if the former were touched by it. It was also
a disinfectant and preventive of infectious diseases. Bruised in water
it relieved weakness of the eyes, and cured liver complaints.
The sapphire was a preventive of despair and fire; a curative
of madness and boils.
The topaz was good for burns, and if thrown into boiling water
deprived it of its heat. It prevented melancholy and cured hemor-
rhages. Its internal brilliancy was believed to follow the phases
of the moon.
Tourmaline when heated was capable of charming away pain, such
as toothache, headache, etc.
A turquois grew pale if its owner became sick, and lost its color
at death until placed upon a princess's finger. It prevented injury
in case of a fall. Held suspended in a glass it told the hour by
strokes against the sides. It was a cheerer of the soul and insured
Such opinions regarding the virtues of gems were not confined to the
lower classes but were held generally. There is little doubt that rulers
were accustomed to carry their gems to the battle-field with them for the
sake of the protection they might afford and victory they might give,
for Charles the Bold lost his gems, among which is said to have
been the Florentine diamond, at the battle-field of Nancy in this way,
and there are other instances indicating that the practice of carrying
gems for this purpose was common.
Another interesting illustration of the regard in which precious
stones have been held is the custom, which survives to some extent to
the present day, of making a particular gem appropriate to a certain
month of the year.
Perhaps the first arrangement of gems into a group of twelve of
which we have any record is that in the Book of Exodus. Here in the
twenty-eighth chapter, verses 17-19, are prescribed in order twelve
precious stones, which shall be set in the breastplate of the high
priest. The list is repeated in the thirty-ninth chapter of the same
book, verses 10-12. In the context it is prescribed that the stones
shall be set in four rows, and that upon them shall be engraved the
names of the children of Israel, one for each stone. As to the par-
ticular gems which are indicated by the Hebrew words, authorities
differ; but in the Authorized Version of the Bible they are given as
Sardius, topaz, carbuncle,
Emerald, sapphire, diamond,
Ligure, agate, amethyst,
Beryl, onyx, jasper.
It is not probable, however, that these names indicate in each case
the corresponding stones of modern usage. Thus, it is quite unlikely
that the Hebrews could have engraved a name upon the diamond
even if they could have obtained one of sufficient size. Again, the
words emerald and carbuncle are undoubtedly interchanged in the
above list, and the ancient topaz is known to have been the modern
chrysolite. In the Revised Version the word jacinth is substituted for
ligure, and amber is given as a marginal rendering for the same. There
are also given marginal renderings for others of the gems as follows:
Ruby for sardius, emerald for carbuncle, carbuncle for emerald, sardonyx
for diamond, chalcedony for beryl, and beryl for onyx. The modern
equivalents of the terms recognized by secret orders which use them
in symbolism are:
Carnelian, chrysolite, emerald,
Ruby, lapis-lazuli, onyx,
Sapphire, agate, amethyst,
Topaz, beryl, jasper.
Two lists of precious stones, quite similar to those of the Book of Exo-
dus, are given in other places in the Bible, one in Ezekiel xxviii. 13,
where " every precious stone " is said to have been the covering of the
king of Tyre, and again in Revelation xxi. 19-20, where twelve differ-
ent precious stones are mentioned as garnishing the foundations of the
wall of the Holy City. The names and order of these in Ezekiel are,
in the Authorized Version, as follows :
Sardius, topaz, diamond,
Beryl, onyx, jasper,
Sapphire, emerald, carbuncle.
To these the Septaguint adds the following:
Chrysolite, ligure, agate.
The Revised Version gives marginally, ruby for sardius, carbuncle
for emerald, and emerald for carbuncle. In Revelation the list as
given in the Authorized Version reads as follows:
Jasper, sapphire, chalcedony,
Emerald, sardonyx, sardius,
Chrysolite, beryl, topaz,
Chrysoprase, jacinth, amethyst.
The marginal renderings give lapis-lazuli for sapphire, and sapphire
Though in each of these lists only twelve precious stones are men-
tioned, there is nothing to indicate that their use was in any way
connected with the months of the year. Just when it became the
custom to designate each month by a particular gem, or how the
custom originated, it is impossible to determine. The custom seems to
have sprung up in modern Europe some time during the fifteenth or
sixteenth century. Whether it originated in the twelve gems of Aaron's
breastplate, as many believe, or was introduced by astrologers from the
Arabians, as others think, is not yet known.
The modern practice of considering the stone of each month espe-
cially appropriate to persons born in that month is probably still more
recent in its origin. In former times gems could be possessed only
by rulers or the very wealthy, so that their general use in the above
manner was not possible. But now that nearly every one can own
a gem of some kind, the possession of "birth-stones," and the attach-
ment of special sentiments to them, has become common. The custom
is a pretty one, and is to be commended, for the stones are imperish-
able, and the sentiments ascribed to them represent the accumulated
traditions of many ages, races, and peoples.
As to the particular stone which is to be considered appropriate
to each month usages differ. Such differences have doubtless arisen
from the desire to introduce gems which were formerly little known
or unattainable on account of their cost, as substitutes for stones for-
merly prized but now held of little value. Thus the precious opal,
now within the reach of all, was rare in former times. By some it
is now used as the birth-stone of the month of October, while others
retain the beryl. The diamond has been introduced in modern practice
in quite a similar way. The carnelian and chrysolite, by some still
used for the months of August and September, are stones held of little
worth at present, and hence others are usually substituted. The par-
ticular order and kind of stones adopted in the colored plate which serves
as a frontispiece to this work is given in accordance with some verses
quoted in a pamphlet first published by Tiffany & Company, of New
York, in 1870. The author of the verses is not known, nor is it known
by just what authority these gems were chosen. The choice, however,
seems as satisfactory as could be made.
By her who in this month is born,
No gems save garnets should be worn;
They will insure her constancy,
True friendship, and fidelity.
The February-born shall find
Sincerity and peace of mind,
Freedom from passion and from care,
If they an amethyst^ will wear.
Who in this world of ours their eyes
In March first open shall be wise,
In days of peril firm and brave,
And wear a bioodstone to their grave.
She who from April dates her years,
Diamonds shall wear, lest bitter tears
For vain repentance flow; this stone,
Emblem of innocence, is known.
v WhQ first beholds the light of day
In spring's sweet flowery month of May,
And wears an emerald all her life,
Shall be a loveoancThappy wife.
Who comes with summer to this earth,
And owes to June her hour of birth,
With ring of agate on her hand
Can health, weaMi, and long life command.
The glowing ruby shall adorn
Those who in July are born;
Then they'll be exempt and free
From love's doubts and anxiety.
Wear a sardonyx, or for thee
The August-born without this stone,
'Tis said, must live unloved and lone.
A maiden born when September leaves
Are rustling in September's breeze,
A sapphire on her brow should bind
'Twill cure diseases of the mind.
October's child is born for woe,
And life's vicissitudes must know;
But lay an opal on her breast,
And hope will lull those woes to rest.
Who first comes to this world below
With drear November's fog and snow,
Should prize the topaz's amber hue
Emblem of friends and lovers true.
If cold December gave you birth,
The month of snow and ice and mirth,
Place on your hand a tmquois- blue ;
Success will bless whate'er you do.
Other groupings of precious stones in lists of twelve are those
which assign one to each of the twelve tribes of Israel and to the
twelve apostles. The list of the former is thus given by Alcott:
Tassin however gives a somewhat different list obtained from an old
silver breastplate employed as an ornament for a manuscript copy of the
Torah, or Pentateuch, used in an ancient synagogue and now in the U.
S. National Museum. This is as follows:
, Reuben -
The list of
the gems of the
is thus given by
James the Less -
The diamond is generally conceded to be the most beautiful as it
is the most important of precious stones. A few other stones exceed
it in value, weight for weight; but in total importance as an
article of commerce other gems are hardly to be compared with
it. Out of thirteen and one-half millions of dollars' worth of precious
stones imported into the United States in 1900, twelve million dollars'
worth were diamonds. Not all this amount was employed for jewelry,
since there is a large utilization of the stone for industrial purposes;
but even for jewelry the diamond has a largely preponderating use.
Its points of superiority are its hardness, its high refractive powers,
and its adamantine luster. In all these qualities it excels any other
known mineral. When in addition to these it exhibits different body
colors, as is sometimes the case, the most highly prized of gems are
In composition the diamond is pure carbon, thus not differing chem-
ically from graphite, or such forms of carbon as lamp-black, bone-black,
etc. It is crystallized, but this can be said of graphite as well. Why
carbon should assume the form of diamond in one case and graphite
in another, as well as being amorphous in other occurrences, is not
known. Such behavior of a substance is known as dimorphism, and
numerous illustrations of it are to be found in nature.
Being pure carbon, diamond can be burned in the air. The finely
divided dust can be burned in the ordinary blow-pipe flame, and for
stones of ordinary size a temperature of about 900 C. is sufficient.
The possibility of consuming the diamond by heat is said first to have
been suggested by Sir Isaac Newton, who reasoned from the high
refractive index of the stone that it was " an unctuous substance
coagulated," and hence probably combustible. Following this sugges-
tion two Italians, Averani and Targioni, succeeded, in 1695, in burning
some diamonds in a furnace, and since then the experiment has been
repeated many times. The diamond does not fuse in burning, but
after becoming heated to redness gradually grows smaller, emitting
sparks, till it entirely disappears. It leaves no ash, except in the
case of the impure form known as carbonado. The gas given off has
been collected and analyzed, and found to be carbon dioxide, just as
would result from the combustion of other forms of carbon. If pro-
tected from the air or free oxygen, the diamond can be exposed to
high heat without change.
Being a crystallized substance and excessively hard, the diamond
is usually found in the form of more or less perfect crystals. These
have forms such as the cube, octahedron, etc., which belong to the
isometric system, and it is in this system that the diamond crystal-
lizes. The crystals do not possess, however, the highest isometric sym-
metry, but belong to the class designated by Groth as hexakistetrahedral,
being tetrahedral with in- clined face hemihedrism.
Of the forms occurring, the / X '\x v octahedron, which is the
first shown in the accom- / V\ panying cut, is best suited
for cutting. It is very /_^^ V^ common for the faces to
be curved instead of flat, \ // an( ^ ^ snow etching
figures of various kinds. \. // The crystals are often con-
siderably distorted so as ^^ to produce pointed and
Common forms of diamond crystals
rounded forms, and twin crystals are common. Although so excessively
hard, the edges of the crystals, as found in the beds of streams, are
often rounded from the wear of the other pebbles, probably chiefly
quartz. Only the wear of centuries could produce such a result, how-
ever; for, as is well known, it is only with its own dust that the
diamond can be abraded to any appreciable degree by any of the
means now used for cutting it.
One important property of crystallized diamond is that of cleavage
parallel to the faces of the octahedron. This cleavage is of much
service in preparing the gem for cutting, as by taking advantage
of it, broad, flat surfaces can be obtained without grinding. This
property also distinguishes diamond from quartz, for which its crys-
tals, as found in sands, are sometimes mistaken. Quartz has no cleav-
age. The fracture of the two minerals is the same however, being
The massive forms of the diamond known as bort and carbonado
possess little or no cleavage, thus increasing their value as abrasives
and for setting in drills, saws, etc. The true bort occurs as rounded
forms made up of a confused aggregate of crystals, and is harder than
ordinary diamond. Fragments of crystals of no value as gems, or any
crude diamond dust, are also known as bort in trade. Carbonado
is a name given to black diamond, which has more or less crystal-
line structure. This graduates into the crystallized mineral. Either
of these is more valuable than the crystallized diamond for industrial
purposes, although of no value as gems.
Usually the diamond is colorless or white, although shades of yellow
are also common. It is also known in shades of red, green, and blue,
and in brown and black. The two latter are rarely transparent, and
grade into bort and carbonado.
About half the diamonds found are tinged to some degree. If the
color is but slight, the stone is considered less valuable than if per-
fectly colorless; but a diamond of pronounced color is the most valu-
able gem known.
Among colors of diamonds, blue is the rarest. The largest and
most valuable colored diamond known is the Hope Blue, weighing
44 carats. This is valued at about one hundred thousand dollars.
It has a brilliant deep blue color and is without a flaw. A deep blue
diamond, weighing 67^ carats, was long worn in the French crown,
but it was stolen in 1792 and has never been recovered. Red diamonds
vary in hue from ruby-red to rose, the latter being the most common.
No large red diamonds are known, the largest being one of 32 carats
in Vienna. Another famous one is that in the Russian treasury,
for which Paul I. paid one hundred thousand roubles. It is of a ruby
color. The finest green diamond known is the "Dresden Green" pre-
served in the Green Vaults of Saxony. It was purchased by August the
Strong in 1743 for sixty thousand dollars. It is apple-green in color
and weighs 40 carats. Diamonds of yellow color are comparatively
common, many of the Cape diamonds being lowered in value by possess-
ing a yellow tinge. It is said that this injurious yellow tinge can be
overcome by dipping the stone several times in a solution of potas-
sium permanganate, the violet color of the latter neutralizing the yellow
of the diamond. The yellow tinge usually also disappears in artificial
light. Of large diamonds possessing a yellow color the Florentine and
the Tiffany are the best known. The color of colored diamonds is gen-
erally permanent, but that of some is said to fade on exposure to light.
It can also be destroyed or changed by heat.
The luster of the diamond is a peculiar one, and such as is possessed
by few other minerals. In reference to its occurrence in the diamond
it is known as the adamantine luster. It combines the peculiarity
of an oily luster with that of glass and that of a metal. It is doubt-
less due to the high refractive power of the mineral, which causes
more than the ordinary number of rays of light to come to the eye.
In the impure forms of diamond the greasy or oily luster becomes
more pronounced. Once the eye becomes accustomed to the peculiar
luster of diamond the stone may easily be distinguished by it from
glass or minerals with a vitreous luster, such as quartz. Certain other
minerals, however, such as cerussite, zircon, and to some extent sphene,
exhibit the adamantine luster. In the glass known as strass, used
to make imitation diamonds, the adamantine luster is well reproduced.
Diamond is usually transparent, but it may be translucent, and even
opaque, especially the black varieties. Even otherwise transparent
diamond often contains inclusions which cloud and interrupt its clear-
ness. These constitute the "flaws" which so often injure the value
of a diamond and prevent it from being of the " first water." These
inclusions may be simply small cavities, sometimes so numerous as
to make the stone nearly black; or they may be particles of other
minerals, such as chlorite, hematite, or carbonaceous matter. If the
latter, the flaws can sometimes be burned out by careful heating.
As already remarked, the refractive power of the diamond is very
high. The rays of light entering it are bent at a high angle, causing
a large degree of what is called total reflection within the stone.
The effect of this is to light the stone's interior. Moreover, the rays
of light are concentrated on a smaller part of the surface than is the
case with less highly refracting minerals, and thus also internal illumi-
nation is produced. The most important result of the high refractive
power of the diamond is the wide dispersion of the spectrum, causing
the red rays to be widely separated from the blue rays, and strong
lights of one color to be transmitted to the eye, as could not be the
case were the different rays less widely separated. It is this power
of flashing different colored lights which gives the diamond one of its
chief charms. The index of refraction ranges from 2.40 for the red
rays to 2.46 for the violet rays. Ordinary glass has an index of refrac-
tion for the red rays of only 1.52, and for the violet 1.54, making the
spectrum only about half as long as that produced by the diamond.
Another pleasing property of the diamond is the fact that it is
usually more brilliant by artificial light than by natural, although some
individual stones have a reverse behavior.
Diamond is much the hardest substance known in nature, and as
the proverb says, only the diamond is able to " cut diamond." It is
ranked 10 in the scale of hardness, corundum being the next below
it. It is really separated by a wide gap from the latter mineral,
however, and its hardness is as much greater than that of corundum
as that of corundum is greater than that of the first mineral in
the scale. This hardness of diamond affords a ready means of
identifying it, as it will scratch all other substances. It is popularly
supposed that diamond is the only mineral which will scratch
glass to any extent, and a stone found is often reported to be
diamond because it will do this. As a matter of fact, however,
all quartz will scratch glass, and the harder minerals, garnet,
topaz, beryl, and others will do so easily. Minerals which will scratch
glass are, therefore, common. The diamond cuts glass instead of scratch-
ing it, and is the only mineral that will do this. Although the diamond
is so hard, it is not tough, and can be easily broken with the blow
of a hammer. It was a tradition of the ancients that if a diamond
were put upon an anvil and struck with a hammer, both hammer and
anvil would be shattered without injuring the diamond in the least.
One occasionally hears this statement made even at the present day.
It is entirely untrue, however, the diamond being as brittle as at least
the average of crystallized minerals.
The specific gravity of the diamond is about three and one-half times
that of water, determinations showing variations between 3.49 and 3.53.
Carbonado is lower, ranging between 3.14 and 3.41. Diamond is thus
a comparatively heavy mineral, the only ones among the gems which
much exceed it in specific weight being hyacinth, garnet, ruby,
sapphire, and chrysoberyl.
Diamond becomes strongly electric on friction, so that it will pick
up pieces of paper and other light substances. It does not retain its
electricity long, however, usually not over half an hour. It is not
a conductor of electricity, differing in this respect from graphite,
which is a good conductor. Diamond becomes phosphorescent on rub-
bing with a cloth, giving out a light which is visible in the dark.
Some stones, as if they took up light from the sun and gave it out
again, emit a phosphorescent light after being exposed to the sun's
rays for a time. This has often been stated to be a property of all
diamonds, but this is not true, only certain stones exhibiting it. As
first suggested by Kunz, it is probable that this phosphorescence is
due to minute quantities of hydrocarbons which are heated by the
friction given the stone. It is curious to note that the light
is in some cases given out only from certain crystal faces. Thus
Map of India, showing diamond fields. After Boutan
diamonds are known which give out light from the cubic faces but
not from the octahedral, while others are reported as giving out light
of different colors from different faces.
''The name diamond comes from the Greek adamas, which means
unconquerable. This term was doubtless applied because of the great
resistant power assigned to the mineral by the ancients. Besides the
well-known tradition that it could not be broken by hammer and anvil,
they believed that the diamond could be subdued or broken down only
when dipped in warm goat's blood. Our words adamant and adamantine
are also derived from adamas, the latter term still being used to describe
the luster of the diamond. The change of adamas into the word diamond
is thought by some to have come from prefixing to it the Italian diafano,
transparent, in allusion to its possessing the property of transparency.
According to classical mythology the diamond was first formed by
Jupiter, who turned into stone a man known as Diamond of Crete,
for refusing to forget him after he had ordered all men to do so.
Many medicinal virtues were ascribed to the diamond, it being regarded
as an antidote for poisons and a preventive of mania.
The world's supply of diamonds has come almost wholly from three
countries India, Brazil, and South Africa. Up to the beginning of the
eighteenth century India was the only source of diamonds known. The
diamond fields of India occur chiefly in the eastern and southern por-
tions of the peninsula. The famed region of Golconda is in the southern
part. This is the territory whence have come the most celebrated Indian
stones, such as the Kohinoor and the Hope Blue. The French traveler
Tavernier reported when he was there in 1665, that sixty thousand
men were then employed in these mines. Now the mines have all
been given up and the region is abandoned.
The present yield of Indian diamonds comes almost wholly from
mines in a district south of Allahabad and Benares. The diamonds
occur here, as universally in India, in a conglomerate or sandstone
made up of the remains of older rocks.
The mines are worked almost wholly by natives of the lower caste,
attempts of Europeans to conduct the mining not having met with
success. The natives separate the diamonds by washing, or where the
rock is too hard for such methods, break it up by heating and throw-
ing cold water upon it. The production of diamonds from all of India
is at the present time very small, not reaching a million dollars a year
in value. It is likely in time to disappear altogether, since most of the
old mines have been abandoned, and even their location forgotten,
and the returns from the present mines are not very profitable.
Most of the famous large diamonds of the world have come from
India, their origin being usually traceable to a period between the
thirteenth and eighteenth centuries. Some of the best known of these
are the Kohinoor, Pitt, Orloff, Great Mogul, Florentine, and Sancy.
The Kohinoor first appeared in history in the year 1304. It was
at that time mentioned as acquired by the Sultan Alaeddin from the
Kajah of Malwa, in whose family it had long been held as an heir-
loom. It was later restored to the Rajah of Gwalior; but on the
defeat of this official, in 1526, by Humairen, emperor of Hindostan, the
stone was presented to the latter by some of the former's adherents. Sul-
tan Baber states that at this time the diamond was valued at " half the
daily expense of the whole world." The stone remained in the posses-
sion of the Mogul dynasty until the invasion of India in 1739 by
Nadir Shah, the Persian conqueror. The reputed exclamation of the
latter when he first saw the stone, "Koh-i-Nur!" ("Mountain of
Light!") gave it the name by which it has since been known.
As the reward of an alliance the diamond was given by the son
of Nadir to Ahmed Shah, founder of the Durain Afghan empire, in
1751. A successor of the latter sought to conceal the stone from
a usurper by embedding it in the plaster of his cell, but after lying
hidden in this way for many years it became exposed and was once
more restored to the Afghan crown. An Indian prince, Runjit Singh,
later obtained the diamond by conquest and brought it to Lahore
where it remained until English rule was established. In 1850 it was
sent to England in charge of two officers. It weighed at that time
186 T Y carats. It had not a symmetrical shape, its cutting being con-
fined, after the usual manner of Indian lapidaries, to fashioning rude
facets on the surface. It also contained two or three flaws. In order
to remove these, and give it a symmetrical shape, the stone was cut
in London, in 1852, by Messrs. Coster, of Amsterdam, to the form
of a brilliant. About 80 carats were sacrificed in this process, and
the stone at present has a weight of 106 carats. The quality of the
Kohinoor is not the finest, it having a slight grayish tinge; but on
account of its romantic history it is one of the most famous, if not
the most famous, of diamonds.
The diamond known as the "Regent" or "Pitt" was found in
India in 1701 by a slave, who to conceal it, cut his leg that he
might put it in the bandage thus made necessary. He thus escaped
with it to the coast, and offered the stone to an English skipper as
payment for passage to a free country. The latter on receiving the
diamond threw the slave into the sea. He then sold the gem to a dia-
mond merchant for five thousand dollars, squandered the money in
dissipation, and went and hanged himself. The diamond was sold by
the merchant to Sir Thomas Pitt, Governor of Fort St. George at
Madras, for one hundred and twenty thousand dollars. When the
latter reached England he found numerous stories afloat to the effect
that he had obtained the gem by foul means. These reports caused
him great distress, both because of their imputation of dishonesty and
because of making widely known his possession of such a treasure.
He developed a morbid fear that he would lose or be robbed of the
gem, and while he possessed it is said never to have slept two nights
under the same roof, and to have gone about much in disguise. During
the stay of the stone in London it was cut into the form of a brilliant,
the cutting reducing its weight from 410 to 136f carats. In 1717 it
was sold to the Regent of France, Duke of Orleans, for about six hun-
dred and seventy-five thousand dollars, which, together with what was
received for the dust obtained in the cutting, made a profit to Pitt
of at least five hundred thousand dollars. The diamond remained
among the French crown jewels till 1792, when it was stolen, in com-
pany with many other precious stones, from the Garde Meuble. Shortly
after a note was received, evidently from the robbers, saying that the
diamond would be found in the Alice des Veuves. In this way the
diamond was recovered, and it has remained in the French treasury
since. It was at one time pledged by Napoleon to the Dutch govern-
ment as a means of securing a loan of two and a half millions of
dollars; but aside from this, its later history seems to have been
uneventful. It is exhibited at present in the Galerie Apollon in the
Louvre in Paris. It is one of the purest and finest of large diamonds.
Its present dimensions are : Length, one and one-sixth inches ; breadth,
one inch; and thickness, three quarters of an inch.
The Orloff diamond is to the Russian crown what the Kohinoor
is to the British. Our first knowledge of this stone is of its forming
one of the eyes of a Hindoo idol. How long it had glittered there
is not known ; but its existence came to the ears of a French grenadier
some time in the eighteenth century. This individual resolved to gain
possession of the diamond by pretending to become a worshiper of the
idol, and so gained the confidence of the Hindoo devotees that they
appointed him special guardian of the god. He shortly improved
the opportunity on a dark and stormy night to tear out the adaman-
tine eye and escape with it to Madras. There he sold it to an
English sea captain for ten thousand dollars and the latter to a Jew
for sixty thousand dollars. The Jew merchant some time after brought
the stone to Amsterdam, where it was seen by Prince Orloff, of Russia,
and purchased for the sum of four hundred and fifty thousand dollars
in cash and an annuity of twenty thousand dollars. By Orloff the
diamond was presented to Catherine II. of Russia, the Czarina, as
a means of restoring him to her favor, he having forfeited this some
time before. Catherine accepted the gift, and the diamond has remained
among the Russian crown jewels since. It is mounted in the Imperial
scepter, and is hence sometimes known as the " Scepter" diamond.
It is the largest of the Indian diamonds now extant, its weight being
193 carats. It has the shape and about the size of half a pigeon's
egg with facets. On one surface is a V-shaped incision, and the stone
has a slight yellow tinge.
Our knowledge of the diamond called the " Great Mogul " is wholly
of the past. It was described by the French traveler Tavernier, as seen
by him in 1665 at the court of Aurung-zeb, a ruler of Hindostan.
Tavernier gave its weight at the time he saw it as 319^ ratis,
i.e., 280 carats; but states that it had been cut from a stone which
weighed in the rough 787|- carats. The diamond is further described
by him as having the form (though not the size, as often stated)
of an egg cut in half, as being rose cut, round, and very high on one
side, and as being of a very pure water. The subsequent history
of the diamond is not known. Attempts have been made to identify
it with the Kohinoor and Orloff; but in the view of Streeter, the emi-
nent English .authority on diamonds, there is no ground for these
views. The "Great Mogul" has probably been either wholly lost,
or it has been cut into smaller stones.
The "Florentine" diamond is also known as the "Austrian Yellow"
and "Tuscan." It has a weight of 139^ carats, and is cut so as to form
a nine-rayed star of the rose form. It is of a citron hue. Its authentic
history is known only back to the time of Tavernier, that writer having
seen it in the collection of the Grand Duke of Tuscany. By the latter
it was transferred to the Empress Maria Theresa, and it has since
remained in the possession of the royal House of Austria. It is often
asserted to have been owned by Charles the Bold, and to have been
lost by him on the battle-field of Nancy or Granson; but Streeter
regards this story incorrect.
/< The Sancy diamond was purchased in 1570 in Constantinople by
M. de Sancy, French ambassador to the Ottoman court. On his return
to France he permitted his sovereign, Henry IV. of Navarre, to use
it as security for a loan, for the purpose of employing & body of Swiss
recruits. But the messenger to whom the gem was intrusted disap-
peared on the way to accomplish his errand, and after some time it
was learned that he had been assassinated. Confident, however, that
he had found some way of guarding the gem, de Sancy had the body
of the messenger disinterred,' and in his stomach the diamond was found. "
Some time after de Sancy sold the diamond to Queen Elizabeth
of England, and it remained in the possession of the English royal
family until about 1695, when it was sold to Louis XIV. of France,
for one hundred and twenty-five thousand dollars. It was stolen in
the robbery of the Garde Meuble, but turned up about 1828, and was
sold by a French merchant to Prince Demidoff. It then went back
to the land of its birth, India, for it was bought by an Indian prince,
in whose possession it either remains, or, according to some authorities, it
is owned by a French syndicate. The Sancy is almond-shaped, facetted
on both sides, and weighs 53^ carats.
After those of India the Brazilian diamond-fields were the first
important ones to become known. The date of their discovery is gen-
erally considered to be 1729. The diamonds were first found in river
sands which had for some time been worked for gold by adventurers
who penetrated into the region from the coast, but who attached no
importance to the little bright crystals sometimes seen in the bottoms
of their gold pans. It is said that a monk who had seen diamonds
mined in India was the first to recognize the nature of the Brazil-
ian stones. The news of the discovery reached the Portuguese gov-
ernment, and the king of Portugal immediately took possession of
all lands likely to be diamondiferous, at the same time inaugurating
a despotic rule which burdened the country for many years. The dia-
monds at first obtained came wholly from the sands and gravels of the
brook and river beds. These sands, universally known by the Portu-
guese word cascalhos, still afford a large part of the supply of Brazilian
diamonds. Extensive upland deposits are, however, now also known.
These are called servicos do campo, while the river deposits are known
as servicos do rio. Several provinces of Brazil afford diamonds, vi/,.,
Bahia, Goyaz, Matto Grosso, Parana, and Minas Geraes. In all these,
except the first and last named, the mining is desultory, and consists
simply in washing river sands by means of wooden bowls. Enough dia-
monds are thus obtained to afford a precarious living to the fiscadores,
as they are called, who follow this occupation. The chief diamond-
bearing region is in the province of Minas Geraes, and the city of Dia-
mantina is its geographical and commercial center. This city is located
about five hundred miles from the sea coast, at the head waters of the
Rio Jequitinhonha and Rio Doce. The valleys of these rivers are
especially rich in diamonds, and form the region which has been
longest and most successfully worked. Here "wet diggings" are car-
ried on in the beds of streams, laid bare by conducting the waters into
Map of principal diamond-fields of Brazil. After Boutan
new channels by means of flames. The work can only be carried on
in the dry season, as in the wet season the quantity of water in the
rivers makes them ungovernable, and sometimes even in the dry season
it happens that a miner has barely got the artificial way constructed
before the waters, increased in volume, suddenly destroy it. The fall of
water from the artificial sluice is often employed to turn a wheel to
keep the old channel pumped dry, but little use is made of this power
for other purposes. When the river bed has thus been laid bare, search
is made with a long iron rod for huge pot-holes, known as caldeiros,
which experience has shown are more likely to contain quantities of
diamonds than the ordinary river bed. This is natural, since the
diamonds resist longer than other stones the constant wear due to the
whirling about of the water in the pot-holes and hence gather there.
It is said that sometimes on removal of a little sand large aggrega-
tions of pure diamonds are to be seen. A single small pot-hole is
said to have yielded 8,000 carats, or about 6 pounds of diamonds.
The caldeiros have now been nearly all dug over, however, and the
finding of a new one is rare. The separation of the diamonds from
the accompanying sand and gravel is usually performed by washing,
in the manner thus described by Gorceix:*
" The sands are placed," he says, " in portions of two hundred
to two hundred and fifty pounds, in a kind of hod or rectangular
trough, only three sides of which are inclosed. The hods are arranged
by twos, fours, or sixes by the side of a trough of water about a foot
and a half deep so that their bottoms shall be slightly inclined toward
it. A workman standing in the trough before each hod dashes water
upon the sand in it. The clay and the very fine sands are carried
away and the first separation is made. The larger pieces remaining
in the top of the sand are picked away. The diamond is to be found
in the two upper thirds of the mass that is left, the lower part being
nearly sterile. The washing is afterward finished in bowls a little
deeper and a little more conical than those used by the gold-washers.
The washer puts the sand in the bowl and fills it with water; then by
whirling the bowl and shaking it up and down while the sand is float-
ing around in it, and being careful to stir it from time to time with
his hand, he determines a classification in the order of density. This
work would be easy if he were washing gold, for that metal is heavier
than the substances with which it occurs, and always goes to the bot-
tom. The diamond, however, having a density only about three and
a half times greater than that of water, not much more than that
of quartz and tourmaline, and less than that of the oxides of iron
and titanium, its constant companions, settles in the middle layers.
The washer, after several rinsings, removes the upper particles, hardly
looking at them; and when he has reached a certain level, which his
* Popular Science Monthly, Vol. XXI., p. 616.
Preliminary concentration of diamond-bearing gravel by dashing water upon it from
broad wooden bowls known as bateas. Near Diamantina, Brazil
Searching washed gravel for diamonds. Near Diamantina, Brazil
skill recognizes at once, tips his bowl slightly so as to let the water
run off in a thin film, and perceiving the glittering crystals of the
diamond picks them out with his fingers. The vigilance of the over-
seers must be redoubled at this stage, particularly when slaves are
employed, for I know of nothing equal to the skill of the slaves in
finding diamonds, except that with which they make them disappear
if the vigilance of the superintendent is relaxed for an instant. I can-
not describe all the artifices employed; but I should remark that since
Agua Suja, Brazil, showing soil worked for diamonds. An example of dry diggings
the works have become free, fraud has greatly diminished. Under the
old rule it overtook half the diamonds in the gravels."
This method of washing is not confined to the river sands, but
is also used to separate the diamonds in the upland deposits. These
upland deposits include strata of considerable extent, composed of clay
derived from the decomposition of a coarse conglomerate. The strata
are divisible into three distinct layers. The first, a soil cap, is some-
what diamondiferous ; the next low^er, a clay called secundina, is regarded
sterile, probably on account of its tenacity, which makes it almost unwash-
able ; while the third, called taua, is the diamond layer par excellence.
Large areas of this sort have been and are still being worked with
more or less profitable returns, an illustration of the latter being given
by Gorceix, who states that he knows of miners who have washed
the cascalhos of Bagagem for twenty years without finding a single
diamond of value.
The origin of the Brazilian diamonds is not well understood. They
do not appear to have originated, like those of South Africa, in eruptive
rocks, as there are little or no traces of such rocks now to be seen.
They were formerly supposed to be constituents of a quartz schist,
called itacolumite, from Itacolumi, a prominent mountain peak near
Diamantina, but this is not now believed to be the case. The present
Director of the Geological Commission of Brazil, Orville A. Derby,
is of the opinion that the diamonds may have been formed out of the
carbon contained in the phyllites (clay schists) of the region by the
intrusion in them of pegmatite veins.
The quantity of diamonds now obtained from Brazil is compara-
tively small, the total production in 1880 being only about forty pounds
(80,000 carats). During the past few years an extensive drought has
prevailed in the diamond-bearing regions, which has favored search
for the stones and increased the output. It is difficult at any time,
however, to learn the exact production, since there is much smug-
gling, owing to the high duty of sixteen per cent levied on exported
The largest diamond from Brazil that is now known is that called
"Star of the South," which weighed in the rough 254.5 carats, and
after being cut, 125 carats. This was found in 1853 by a negro slave
woman. It was a dodecahedron, and has a peculiarity that no other
diamond possesses, in giving off in certain lights a rose tint, although
perfectly white itself. It was sold for one hundred and seventy-five
thousand dollars to a Paris syndicate, which is said in turn to have
sold it to an Indian prince.
The next great deposit of diamonds to be found after that of Brazil,
and by far the most important known to-day, is that of South Africa.
The first discovery of diamonds here is to be credited, as has so often
been true in the finding of gems, to the picking up of pretty stones
by children. Among such pebbles gathered by a child of Daniel Jacobs,
a Boer farmer living near the present town of Barkly West on the
Vaal River, one was thought by John O'Reilly, a roving trader, to be
a diamond. To test the matter he sent the stone to Dr. Atherstone,
a mineralogist at Grahamstown, who at once identified it as a veritable
diamond, and expressed the belief that more were likely to be found
in the region. This find was made in 1867, but no more diamonds
were discovered until March, 1869, when a superb stone weighing
S3 carats, and which not long after brought a price of one hundred
and twenty-five thousand dollars, was picked up in the same region.
This discovery was sufficient to set a tide of diamond-seekers toward
the valley, and soon their camps were spread all up and down the
Vaal River. The separation of the diamonds from the gravel was
at first performed by hand panning, after the method of the Brazilian
and Indian miners; but after a time a piece of apparatus consisting
of a long box with a sieve bottom, mounted so that it could be swung
back and forth, came into use. This was called sometimes a "baby"
and sometimes a "cradle." The meshes of the sieve were of such
size as to allow the fine refuse to pass through, while the medium-
sized pebbles likely to contain diamonds were retained and rolled into
a tub. The contents of the latter after shaking were turned upon
a "sorting table" and the diamonds picked out by careful scraping.
By use of this apparatus a larger quantity of the gravel could be
shaken at a time with less labor. In this way large areas of the
gravel beds of the valley were sorted over for diamonds. It soon
appeared, however, that though the extent of the diamond - bearing
gravels was great in area it was small in depth, and though large
numbers of men found profitable employment there for a time, if no
other source of supply had appeared diamond-mining in South Africa
would probably long ago have been a thing of the past. But in
August, 1870, a farm overseer by the name of De Klerk, living at Ja-
gersfontein, having learned that diamonds were usually accompanied
in the river diggings by garnets, and having found some of the latter
on his farm, went to work with a common wire sieve, and at a depth
of six feet found a fine diamond of 50 carats. A month later a similar
discovery was made at the place now called Kimberley, and further
and deeper digging only disclosed more and more of the diamonds.
The news of these discoveries spread rapidly, and soon the farms on
which the diamonds had been found were staked out in claims by
hordes of diamond diggers. The returns from the diggings proved
profitable ; but the diamond-bearing areas were so small that the intri-
cacy of the claims within them became a serious matter. At first roads
were left by common consent between the claims to provide means
of transportation and places for work, as shown in the accompanying
view of the Kimberley mines in 1872.; but as the roads were too full
of diamonds to be spared, they were in time cut away, and the plan
was adopted of removing the diamond-bearing earth by means of cars
carried by long wire ropes to the surface. Each claim or owner had
his own system of pulleys, and the mines soon came to look as if covered
by a vast spider's web. In ] 885, within an area of seventy acres, at Kim-
berley forty-two companies and fifty-six private firms or individuals
were working. As the diggings grew deeper the situation became
more and more serious because of the different depths to which differ-
ent claims were carried. The walls of the outlying areas disintegrated
rapidly, and fell from time to time in great masses, causing sad loss
of life. Moreover, the immense output of diamonds, and extensive
competition between the different producers, caused a lowering of the
price which made it unprofitable to work many of the poorer parts
of the mines. A consolidation of interests seemed the only way out
of these difficulties, and this was finally accomplished under the leader-
ship of Cecil Rhodes. In 1888 a joint stock company, known as the
De Beers Consolidated Mines, Limited, was formed to operate the impor-
tant diamond properties in the region of Kimberley. The workings
of this company have proved highly satisfactory, both in promoting
a safe and economical extraction of the diamonds and in limiting
their output. Under the new management the system of open-cut
workings has been abandoned in all the mines except the Premier,
and the diamond - bearing ground is mined by a system of tunnels
at various levels. From these it is hoisted to the surface through
shafts, and then spread out over large areas, called floors, to disinte-
grate. The disintegration is accomplished by exposure to sun and
rain, huge harrows being drawn frequently over the floors to assist
in the work. The time required for proper disintegration varies from
three to six months according to the nature of the rock. When suffi-
ciently disintegrated, the rock is carried to machines which wash away
the finer particles and mechanically concentrate that of a size likely
to contain diamonds of value.
For a long time the diamonds were picked out from this concen-
trate by hand, the assortment of pebbles being spread on tables and
picked over. It has lately been found, however, as already noted,
that by running the concentrate over percussion tables the surfaces
of which are covered with a thick coat of grease, that the diamonds
are caught and held by the grease while the valueless minerals pass on.
In this way a more nearly complete as well as more rapid extrac-
tion of the diamonds is secured than when the concentrate is sorted
After being sorted out the diamonds are cleaned by boiling in a mix-
ture of nitric and sulphuric acids, rinsing in water, and finally washing
in alcohol. They are then assorted according to quality into about ten
classes, ranging from the finest, called ll close goods," to the poorest,
called " boart." The diamonds belonging to the first eight of these
classes are then again assorted according to color, the " blue whites "
standing first and the "yellows" last. They are then wrapped in
parcels and forwarded to London, where they are reasserted and sup-
plied to the trade. The color, size, and quality of the diamonds from
the different mines vary considerably, but are fairly constant for each
mine. A majority of the diamonds from the De Beers mine, for instance,
are "yellows," colorless stones being almost never found there. The
Dutoitspan mine, on the other hand, produces many blue-white and
white stones, and these are generally of large size. The iiamonds
o */ o
of the Jagersfontein mine excel all others in quality, superb blue-white
stones being the rule.
From the South African mines have been obtained the world's
largest diamonds, unless the mythical "Grand Mogul" and question-
able " Braganza " are to be excepted. The largest and finest of 1 the
South African stones, also the superior of any other known diamond,
is that called the "Jubilee" or " Excelsior." This stone weighs 239
carats, and was cut from a crystal of 9 7 If carats found at Jagers-
fontein in 1893. It is cut as a brilliant, and has the following dimen-
sions: Length, If inch; breadth, If inch; depth, 1 inch.
Other noted South African diamonds are the "Tiffany," a yellow
diamond weighing 125^ carats; the "Star of South Africa," already
mentioned as found in 1869, and now cut to a size of 46^ carats;
and the "Victoria," a stone of 180 carats, cut from an octahedron
weighing 457^ carats.
Turning to a consideration of the geological characters of the dia-
mond-bearing areas, it may be stated that each is approximately spheri-
cal or oval in form, with an average diameter of two hundred to three
hundred yards. The four principal mines are embraced within an area
four miles square. The areas in which the diamonds were found were
originally somewhat depressed, giving to them the name of "pans." The
upper portion of the area was a friable mass of a yellow color called
"yellow ground." On going deeper the color of this portion changed
to a blue or greenish blue, and the rock became firmer. It is this
" blue " or " blue ground " which, now that the yellow ground has
become exhausted, furnishes all the diamonds. The strata which inclose
it are, as illustrated in the accompanying figure, at the top, a layer of
basalt about fifty feet in thickness ; below this two hundred to three
hundred feet of a nearly horizontal black, carbonaceous shale; next
a thin conglomerate; next about four hundred feet of a dark rock
called at first melaphyre, but now regarded as olivine diabase; and
finally a quartzite which extends as far as exploration has gone. The
relation of the diamond-bearing ground to these strata seems to be in
the nature of a volcanic intrusion. The diamond-bearing or " blue
ground " is a breccia, consisting largely of chrysolite more or' less altered
to serpentine, and accompanied by bronzite, pyrope, diopside, zircon?
cyanite, mica, pyrite, magnetite, ilmenite, and some other minerals.
There are also fragments of shale and boulders of varying composition
in the blue ground.
The origin of the diamonds in the blue ground has naturally been
the source of much speculation, but no theory meets general accept-
ance as yet. One of the first suggestions was that of Professor Henry
Carvill Lewis, of Philadelphia, that the heat of the volcanic intrusion
Section of De Beers diamond mine, South Africa, showing character of strata. The "blue
ground " is the diamond-bearing area
transformed the carbon of the surface shales into diamond. This theory
seems untenable, however, for many reasons, as shown by Mr. Gardner
F. Williams in his recent work. Mr. Williams states that about the
diamond-bearing deposits at Jagersfontein there are no such shales,
while in the regions where they do exist there is no alteration observ-
able at the junction of the shales and blue ground, nor among the
fragments of shale inclosed in the blue. According to another theory
the blue ground is not of igneous origin, but is a sort of mud forced
up by hydrostatic pressure. This brought up the diamonds from depths
below. The present trend of opinion seems to be that the origin of the
diamond was deep-seated; but whether its matrix was the basic rock
in which it is now found or some other is not known. Professor
T. G. Bonney, who has given much attention to the matter, , is of the
opinion that the diamonds were originally connected with eclogite,
a metamorphic rock carrying somewhat more silica than character-
izes the present blue ground, and containing considerable garnet.
About ninety-five per cent of the world's supply of diamonds comes
at the present time from the South African mines, their annual pro-
duction being about 2,500,000 carats. Other countries which produce
small quantities of diamonds, besides those already mentioned, are
Borneo, Australia, British Guiana, and the United States.
The diamonds of Borneo come from two portions of the island,
one field being in the western and the other in the southern part.
These fields have been known and worked from time immemorial;
but have afforded only a small supply, the product varying from
tw r o thousand to six thousand carats annually. In the western part
of the island the diamonds occur in alluvial gravels, and their parent
rock is not known. In the southern part they occur in a conglomer-
ate overlying strata of Eocene age. The majority of the diamonds
obtained are small and of rather poor quality. Their mining is per-
formed in a desultory way by native Malays and Chinese, and the
supply seems gradually to be decreasing.
The first discovery of diamonds in Australia was made in 1851 in
placer gold-mining in New South Wales. The locality was not far
from Bathurst. Since then in this locality, and the neighboring head
waters of the Macquarie River, a number of small diamonds have been
found. The largest number were found along the Cudgegong River,
northwest of Mudgee, in an old river drift covered with basalt. About
2,500 stones were obtained there in 1869. Accompanying the dia-
monds are gold, garnet, zircon, tinstone, or cassiterite, tourmaline, and
magnetite. The gold and diamonds are obtained as in California by
tunneling under, the basalt so as to excavate the gravels. Another
locality in New South Wales which has yielded diamonds is in the
vicinity of Bingera. Here the diamonds occur in gold and ruby-bearing
sands, the accompanying minerals being quite similar to those men-
In Southern and Western Australia and in Tasmania a few dia-
monds have also been found. The Australian diamonds are all small,
none of over 6 carats weight being known. The yield from New South
Wales in 1899 was reported to be 25,874 carats.
Small diamonds have been found at several points in the Ural Moun-
tains. The first were obtained about 1829 in the vicinity of Bissersk,
Government of Perm, occurring in alluvial sands with gold, platinum,
quartz, magnetite, and anatase. It is said that Alexander Humboldt
predicted the finding of diamonds here from the similarity of the
gravels to those of Brazil in which diamonds are obtained.
Later finds of diamonds have been made near Ekaterinburg and
in Werchne Uralsk and Troitzk in the Government of Orenburg;
likewise in connection with auriferous sands.
Diamonds have also been found in Lapland in the vicinity of Var-
anger Fjord on the Arctic Sea. They occur in river sands, together
with garnet, quartz, rutile, and other minerals usually found accom-
panying diamond. These diamonds are small and scarce.
British Guiana has recently come into prominence as a field which
may produce a profitable supply of diamonds. Small stones were first
found here about 1890, and work has been continued until now a con-
siderable amount of mining is carried on. The locality is along the
Upper Mazaruni River, two hundred and fifty miles south of the town
of Bartica. The journey to it is a long and difficult one, all supplies
requiring to be transported over a narrow trail through a tropical
jungle. The diamonds occur in a formation of sandy clay with other
pebbles and ironstone nodules. They are separated by washing the clay
in sieves of one-sixteenth inch mesh to remove the fine particles, and
are then picked out by hand. The yield is quite remunerative, nine
men having in one instance obtained four hundred stones by working
eighteen days. The stones are small in size, few being above two carats
weight, but they are of good quality. Several companies have been
organized to work the deposits, and a measurable output is likely to be
The occurrence of diamonds in the United States is largely confined
to two regions ; the first a belt of country lying along the eastern base
of the southern Alleghanies from Virginia to Georgia, while the other
extends along the western base of the Sierra Nevada and Cascade
ranges in northern California and southern Oregon. There is also
a third, of less importance, belonging to the Kettle moraine district
of southern Wisconsin. One of the diamonds found in the southern
Alleghanies weighed 23f carats. It was found in 1855 at Manchester,
Virginia, and is usually known as the Dewey diamond from the name
of its one-time owner. Eight or ten diamonds, varying from one to four
carats in weight, have been found in various localities in North Carolina ;
ten or twelve counties in Georgia have furnished one or more small
stones, and one or two are reported from South Carolina. These dia-
monds have all been found loose in gravels, and have been obtained
either while washing the gravels for gold, or in digging wells, or they
have been picked up by children. A resemblance of certain strata in
GLACIAL MAP OF THE GREAT LAKES REGION.
Ol.de IT Dvi I L.
Glaoial Striae .
Newer- Drii t
El, Eagle. O, Oregon,
i-ii Cvlf.. B Surlin.(i,toi-L
North Carolina to the itacohnnite of Brazil, in which diamonds are
found, has at times been urged as indicating that these may have
been the source of the diamonds, but no discovery of such stones has
yet been made in this formation. The diamonds of the Kettle moraine
region of southern Wisconsin have all been discovered since 1876.
They have been obtained at six localities in Wisconsin, and one locality
each in Michigan and Ohio. Seven good-sized diamonds have been found,
the largest weighing 21^ carats, and one locality has yielded numerous
small stones. The diamonds were obtained in gravels of glacial origin,
and Hobbs has shown, from a study of the directions of glacial move-
ment, that the original source of the gems may have been the territory
lying southwest and south of Hudson's Bay. The localities where the
diamonds were found, and the probable course of their distribution
southward, are shown on the accompanying map.
The diamonds of California have been found in connection with .
gold-bearing gravels, the gravels being sometimes those buried under
lava flows. In Amador, Butte, El Dorado, Nevada, and Trinity counties
diamonds have been found, the stones rarely exceeding two carats in
weight, but being generally of excellent quality. The accompanying
minerals have been zircon, topaz, quartz, epidote, pyrite, chromite, etc.
The diamonds are discovered in washing for gold; but the yield has
never been sufficient to repay search for them alone, nor is it likely
ever to be. In one or two localities in Oregon, Idaho, and Montana
diamonds have been similarly obtained.
Numerous attempts have been made to produce the diamond artifi-
cially, some of which have been attended with success, although no stones
large enough for industrial or ornamental use have yet been made.
Moissan, of Paris, in 1893 succeeded in producing diamonds by heat-
ing iron saturated with carbon to a high temperature, and then sud-
denly cooling the exterior of the mass. This exterior cooling caused
an intense pressure on the interior, whence black diamonds of micro-
scopic size were produced as a result of the heat and pressure, as it
Still more recently, von Hasslinger has obtained diamonds by fusing
a mixture corresponding in composition to the South African diamond-
bearing breccias. The diamonds were small, not exceeding .002 of an
inch in diameter, but they were colorless and transparent crystals.
The success of these experiments gives some reason to believe that
fair-sized diamonds may in time be produced artificially.
(RUBY, SAPPHIRE, ETC.)
The mineral species corundum affords a number of gems known by
different names because the stones were used as gems before their miner-
alogical identity was discovered. Thus the ruby is red corundum and
sapphire blue corundum. When corundum suitable for gem purposes
occurs of other colors, such as green, yellow, or violet, the gems are
sometimes known as green, yellow, or violet sapphires, respectively,
or by the name of another gem which they closely resemble in color,
with the adjective "Oriental" prefixed. Such are the gems known
as Oriental topaz, Oriental emerald, Oriental aquamarine, Oriental hya-
cinth, Oriental amethyst, and Oriental chrysolite. Colorless corundum
is known as leucosapphire. While corundum of all colors is used for
gems, it is only that which is transparent which can be so employed.
This is sometimes called noble corundum to distinguish it from common
corundum. The two, however, often occur together. Common corundum
is used as an abrasive, emery being one of its varieties, but it has no
Corundum is a sesquioxide of aluminum, with the percentages, alumina
53.2, oxygen 46.8. Its hardness is 9 in the scale, and no mineral except
the diamond equals it in this respect. This hardness gives it a wear-
ing quality as a gem second only to the diamond. The varieties
of corundum differ slightly in hardness, sapphire being the hardest.
Noble corundum has a brilliant, vitreous luster, which, while not equal
to that of the diamond, is superior to that exhibited by almost any
other gem. Corundum is a heavy mineral, its specific gravity being
four times that of water. This high specific gravity affords an easy
means of distinguishing gems of corundum from those of other species.
Corundum is infusible, and is not attacked by acids. It crystallizes in
the rhombohedral division of the hexagonal system, certain crystal forms
being characteristic of the two varieties, ruby and sapphire. Thus ruby
tends to crystallize in flat rhombohedral crystals, while sapphire generally
forms in longer hexagonal prisms. (See colored plate.) Corundum
is doubly refracting and dichroic. Of the different colors of corundum
above referred to, the blue or sapphire is most common, the red or ruby
next. The other colors occur rather sparingly, green having been almost
unknown until the discovery of the Montana sapphires. The nature of
the coloring ingredient of the different varieties of corundum is not
known, but there is some reason for believing it to be chromium, for
Fremy obtained artificial red and blue corundum by mixing chromium
with his other ingredients, after many other attempts to obtain the
desired color had failed.
Red corundum varies in hue from rose to deep red. That of the
latter tint is the true ruby, the color known as pigeon's blood being most
highly prized. Faultless stones of this color have long been the most
valuable of gems, exceeding the diamond in price, weight for weight.
At the present time they are worth between $2,000 and $3,000 per
carat. The writer recently saw a ruby of nine carats in the possession
of a Chicago jeweler which is valued at $25,000, and one of eleven
carats is reported to have been lately sold for $80,000. But few rubies
exceeding ten carats are known. The King of Pegu is reported to have
one the size of a hen's egg, but as no one has ever seen it the story
may well be doubted. In the crown of the Empress Catherine was, how-
ever, one the size of a pigeon's egg. There is also a large uncut ruby in
the British crown, said to have been given to Edward, Prince of Wales,
by the King of Castile, in 1367. Ruskin calls it the loveliest precious
stone of which he has any knowledge. This is probably, however, a
spinel ruby, not a corundum ruby.
The chief home of the true ruby is Burmah. From its mines and
those of Siam and Ceylon have come practically all the world's supply.
The most important Burmese mines are in Mogouk, ninety miles north
of Mandalay. The rubies were evidently formed here in limestone, which
is now much decomposed, and seem to have been the result of metamor-
phism of the limestone by the entrance of eruptive rocks. The ruby-
bearing earth is known as " by on," and the gems are obtained from
it by washing. They are usually in the form of more or less complete
crystals. The mines have been worked since the British occupation
of Burmah in 1886, by a British company, and there can be little doubt
that a desire to acquire these mines was one reason for the occupation.
The mines have not proved very profitable, however, and only within the
last year or two has the company been able to pay any dividends. The
hope of success has lain in the introduction of machinery for washing
the byon more cheaply than it could be done by the primitive native
methods, and it is now believed by the introduction of an electrical
power plant that this has been accomplished. This company now pro-
duces at least one-half the annual yield of rubies of the world.
Bed of ruby-bearing gravel at Caler Fork, Cowee Valley, Macon County, North Carolina
Washing gravel for rubies, Cowee Valley, Macon County, North Carolina
Previous to the working of the mines by the English the mining
was performed by domestic labor under control of the native govern-
ment, all rubies above a certain size going to the king. Whenever
a ruby of unusual size was found a procession of grandees, with soldiers
and elephants, was sent out to meet it. One of the titles of the King
of Burmah was Lord of the Rubies.
-The Siamese rubies come from near Bangkok, on the Gulf of Siam.
They occur in a clay which seems to be the product of alteration of a
basalt. These rubies are not equal in quality to those of Burmah.
Rubies are also found in the gem gravels of Ceylon, and in Afghanistan,
thirty-two miles east of Cabul.
In our own country ruby corundum is occasionally found in connec-
tion with opaque corundum in Macon County, North Carolina. In the
gravels of Caler Fork of Cowee Creek of this county good rubies are
found in sufficient quantity to reward systematic mining for them.
They are known as "Cowee Creek" rubies.
The gravels containing them are " washed" by methods described by
Dr. J. H. Pratt as similar to those used in the West for washing gold-
bearing gravels. Both the gravel and the soil which overlies it are
washed into a line of sluice boxes which lead into a sieve box. From
the latter the dirt and fine gravel are. washed away. The material that
remains is shoveled into a rocker, into the bottom of which the rubies,
being heavier, gradually work, and are then removed by hand picking.
These rubies are mostly small, but some gems of three or four carats'
weight and of excellent color have been obtained.
Among the Montana sapphires an occasional red stone is found, but
they do not have the choicest red color.
Another source of rubies is their artificial production, after the method
discovered by the French chemist Fremy. The artificial rubies are made
by heating a mixture of aluminum sesquioxide, carbonate of lime, barium
fluoride, and potassium chromate in a porous clay crucible to a tem-
perature of 1500 C., and keeping the mixture fluid for eight days.
Well -formed, clear crystals up to one -third of a carat in weight
tre thus produced, which have the hardness and color of native ruby.
They are not considered so valuable as gems as the latter, and can
usually be distinguished by the minute air bubbles which they contain.
The expense of making them is nearly equal to the value of native
rubies, so that their production is likely to be limited.
Other substitutes for the ruby are garnet, that from South Africa
being known as Cape ruby, hyacinth, red tourmaline, known as Siberian
ruby, rose topaz, sometimes known as Brazilian ruby, and spinel. None
of these is as hard as the ruby, and each differs sufficiently from the
ruby in its refractive powers, or specific gravity, to make distinc-
Rubies were known to the ancients, being mentioned in the Bible in
Proverbs and Job. The Greeks and Romans ascribed to the ruby the
power of giving light in the dark, and the Hindoos describe the abodes
of their gods as thus lighted. The ruby was much worn as an amulet,
being supposed to protect the wearer against plague, poison, and evil
spirits. It was also thought that it would turn dark if its owner
were in danger, and would not regain its color until the peril was
over. The Burmese believe that the ruby ripens like fruit. The crude
are colorless; thence they grade yellow, green, blue, red.
The ruby is usually cut in the form of the brilliant, like the dia-
mond, but sometimes the step cut is advantageously employed. The
native gem -cutters of India do not cut facets on their rubies, but
simply round and polish them.
Blue, precious corundum, or sapphire, is more abundant than the
red or ruby. Like the red, the blue color seems to be due to a con-
tent of chromium, since in the artificial crystals already mentioned
as produced by Fremy, both colors occur at times in the same crystal.
This occurrence of two colors in single crystals is also found in
Nature, some being red at one end and blue at the other; or, perhaps
what is more frequent, the center of the crystal may be yellow and
the exterior blue. This coloring is not uncommon among the Australian
sapphires, and unique gems are obtained by cutting them so as to show
the two colors. Bauer describes a figure of Confucius carved from
a sapphire, of which the head is white, the trunk and arms blue, and
the legs yellow. The color of sapphire most highly prized is that
known as cornflower-blue. The cornflower (Centaurea cyanus) is also
known in this country by the name of " bachelor's button," and excel-
lently typifies the true sapphire color. Other shades of blue which
occur in the sapphire, are indigo-blue, smalt-blue, berlin-blue, and
greenish and grayish blues. The sapphires of darker colors are usually
known as male and those of lighter colors as female sapphires. In
addition to possessing the true corn-flower blue color, the best sapphires
should exhibit a velvety sheen, the value of the stone being greater
the more perfect this character.
As already noted, sapphire is somewhat harder than ruby, and it
is also somewhat heavier. The Montana sapphires are said to be espe-
Sapphires have at the present time not over half the value of a ruby
Corundum mine from which some sapphire is obtained
Corundum Hill, Macon County, North Carolina
of the same size. A price of forty dollars per carat is an average one
for a small stone; and as much larger stones are comparatively
common, the price does not increase so rapidly as does that of the
ruby with an increase in size.
The world's supply of sapphires comes chiefly from Siam. The most
important mines of that country are those of Battambong, a city south-
east of Bangkok. The sapphires occur in a sandy clay, out of which
they are washed. The sapphire-bearing region is about a hundred miles
in length. Together with the sapphires occur some rubies, especially
in the southern part of the district. Sapphires also occur among the
rubies of Bur mail, but in small numbers. The so-called gem gravels
of Ceylon furnish many sapphires, though their quality is not equal
to those of Siam, because of paleness of color.
Another locality for sapphires, discovered about 1882, is Banskar,
in Cashmere, India. These stones were first disclosed by the fall of an
avalanche, and later were discovered to exist in the region in consider-
able numbers. For a time they could be cheaply purchased, but are
now jealously guarded by the government.
The Montana sapphires have been known since 1865, but were not
systematically worked until 1891. They occur in river sands east
of Helena, and were first obtained in washing for gold. Now the
mother rock has been discovered; and this is mined, the rock being
taken out, piled in heaps, and submitted to the action of frost through
the winter. The sapphires thus become loosened and can be readily
separated. These sapphires are well crystallized and are of good aver-
age size, though few gems exceed six carats in weight. Their luster
and color are for the most part of first quality, and the stones are in
demand for the best of jewelry. The most recent find of sapphires
has been in Central Queensland, Australia, at a place called "^Anakie,
twenty -six miles west of Emerald. Here sapphires occur over an
extensive area. Green, yellow, pale blue, and dark blue stones are
those most commonly found, the cornflower-blue occurring but rarely.
Hence, the stones have not been widely used as yet. They reach sizes
of from thirty to fifty carats.
The common corundum of North Carolina, mined extensively as an
abrasive, often also contains blue transparent portions from which gems
can be made. One of the best known mines yielding such stones is that
at Corundum Hill, in Macon County. This also produces a few rubies,
and a fine specimen of Oriental emerald, or green sapphire, was obtained
here. This was a crystal 4 by 2 by 1 3- inches, which would afford
several first-class gems.
Noble corundum of other colors than those of blue and red is not
of abundant occurrence, nor is it ordinarily as highly prized as are
the sapphire and ruby. Colorless sapphire, or leucosapphire, is some-
times used as a substitute for the diamond, from which it can readily
be distinguished by its lower hardness and higher specific gravity.
Certain specimens of both sapphire and ruby, but especially the
former, exhibit when polished a six-rayed star. This appears as beams
of light, radiating from a center which changes in position as the stone
is turned. Such stones are called star, or asteriated sapphires, or rubies,
and are highly prized. They are usually cut with rounded surface,
as this best brings out the figure. The cause of the star-shaped figure
is generally supposed to be the total reflection of light from countless
microscopic cavities in the stone, which are arranged parallel to the
faces of a six-sided prism. Some authorities believe, however, that mul-
titudes of twining lamellae similarly arranged cause the appearance.
Burton, the African traveler, is said always to have carried a star
sapphire about with him, as a means of winning respect from the
barbarous peoples among whom he journeyed. The savages believed
that the stone must be a talisman of great power and feared to incur
its owner's enmity.
Sapphire is a word which is the same in nearly all languages,
a fact which testifies to the ancient use of the stone. In Chaldean,
Hebrew, Greek, and Latin the word has the same form as in mod-
ern tongues. In early times sapphire was believed to be a destroyer
of poison, so that if put into a glass with a spider or venomous reptile
it would kill it. It was regarded also as a remedy against fevers
if placed on the heart, or soaked in vinegar and the extract admin-
istered. The wearer of a sapphire was rendered by it chaste, virtuous,
pious, devout, and wise.
(RUBY SPINEL, BALAS RUBY)
The group of spinel includes in mineralogy a number of species of
different though analogous composition. The spinel employed as a gem
is almost wholly a magnesium aluminate, having the percentage composi-
tion: alumina 71.8 and magnesia 28.2. This is usually of a red color,
different shades giving gems known by different names as follows : Deep
red, spinel-ruby; rose-red, balas ruby; yellow or orange red, rubicelle;
violet-red, almandine ruby. Spinel is thus known among gems chiefly
as a relative of the ruby, and this sort of spinel will first be con-
The spinel rubies differ from the true or corundum rubies in hard-
ness, specific gravity, and system of crystallization. The hardness of
spinel is 8, or about that of topaz, and the specific gravity 3.6. It is
thus neither as hard nor as heavy as corundum ruby. Again, the system
of crystallization differs. Spinel crystallizes in the isometric system, and
is usually found in the form of octahedrons, while corundum ruby is
hexagonal in crystallization. (See colored plate.) Spinel is singly refract-
ing in polarized light, and corundum doubly refracting. Spinel ruby is
infusible before the blowpipe, but on heating undergoes a curious series
of changes in color which are quite characteristic. The red changes
first to brown, and then becomes black and opaque, but on cooling the
black changes to green, then becomes nearly colorless, and finally the
stone resumes its original red color. As a small percentage of chro-
mium is usually found by analysis to exist in ruby spinel, its color is
generally considered to be due to this ingredient. While the spinel ruby
is considered of less value than the corundum ruby, and is sometimes by
fraud or error substituted for the latter, it yet has a definite value as a
gem when sold under the name of spinel ruby or some of its varieties.
This value is usually reckoned at about half that of the corundum ruby,
although variations in quality of the stones, as well as changes in demand,
cause differences of price. Thus Emanuel mentions a spinel ruby of good
quality weighing 40 carats, which in 1856 was sold for $2,000, but
in 1862 brought at public auction only $400. In 1866, however, it was
again sold for $1,200. A spinel ruby among the French crown jewels,
weighing 56 carats, was in 1791 valued at $10,000. This is much more
than such a stone would now probably be worth.
Not only is spinel ruby related to corundum ruby in color and use,
but the two are frequently associated together in nature. The gem
gravels of Ceylon, Siam, Australia, and Brazil contain both kinds of
rubies, and the ruby mines of Upper Burmah, where the corundum ruby
occurs in a crystalline limestone, produce also large quantities of spinel
rubies. Spinel rubies also come in large quantity from 'Badakschan, in
Afghanistan, near the river Oxus, the name of balas rubies, by which
they are often known, being said to be derived from Beloochistan,
another form of which word is Balakschan. The Persians have a tradi-
tion regarding these mines, that they were disclosed by an earthquake
which rent the mountain in twain.
The localities above mentioned furnish nearly all the spinel rubies
of commerce. A few have been found in North America, Hamburgh,
New Jersey, and San Luis Obispo, California, being two localities where
small crystals have been obtained, but they have never afforded any
appreciable supply. No spinel rubies of great size are known. Bauer
mentions as the largest known, two cut stones, one of 81 carats, and
the other 72^ carats, exhibited at the London Exposition of 1862. The
King of Oude is said at one time to have possessed a spinel ruby the size
of a pigeon's egg. Another celebrated spinel ruby is that known as the
' Ruby of the Black Prince," which is shown among the English crown
jewels in the Tower of London.
Spinel occurs in many other colors besides red, such as orange, green,
blue, and indigo, as well as white and black. Occasionally colorless
spinels occur, and as they cannot be distinguished by their behavior in
polarized light from the diamond, it is sometimes sought to substitute
them for the latter. They can be detected at once, however, by their
inferior hardness. While spinels of any color, if transparent and free
from flaws, make desirable gems, the only colors found in sufficient quan-
tity outside of the red to make an appreciable supply are the blue and the
black. The blue spinels resemble the sapphire in color, though they are
somewhat paler. They come chiefly from Ceylon and Burmah, where
they occur together with the ruby spinel. The black spinel is known as
ceylonite, or pleonaste, and is also obtained chiefly from Ceylon, although
occurring of a quality suitable for cutting at Mount Vesuvius in Italy.
Like the ruby, spinel can be made artificially, the process being to
heat a mixture of alumina and magnesia with boracic acid, and if a red
color is desired, a little chromium oxide. No attempt seems to have been
made as yet, however, to manufacture it for gem purposes.
The spinel ruby seems to have been known to the ancients equally
with the corundum ruby, and the two were probably often confounded.
The natives of India call the spinel the pomegranate ruby, and believe
to this day that it possesses valuable medicinal properties.
In the Middle Ages it was believed that if one touched with this
gem the four corners of a house, orchard, or vineyard they would be
protected from lightning, storms, and blight.
The Arabs had a tradition that sea cows gathered spinels from the
Kokaf Mountains, and left them on the ground in Ceylon. Stone-gath-
erers would then throw lumps of clay over the gems, and leave them
until the cows, " disappointed at not finding the stones, and fretting and
fuming with rage," returned to the sea, when their human rivals would
come and get the stones.
(EMERALD, AQUAMARINE, ETC.)
This mineral species includes a number of varieties which are highly
valued as gems. These are, besides beryl itself, the gems emerald,
aquamarine, and golden beryl. Of these, emerald is dark-green beryl,
aquamarine bluish-green, or greenish-blue beryl, and golden beryl,
yellow beryl. . Chrysoberyl is not a variety of beryl.
While these varieties of beryl all differ in color, they are the same
mineral, and are practically identical in composition, hardness, and other
properties. In composition, they are a silicate of aluminum and glucinum,
the percentages being, for normal beryl: 67 per cent of silica, 19 per cent
of alumina, and 14 per cent of glucina.
The beautiful green color of the emerald is probably due to a small
quantity of chromium which it usually contains, though some authori-
ties believe organic matter to be the coloring ingredient. To what
substance the other varieties of the species owe their color is not
In hardness the varieties of beryl differ little from quartz, the hard-
ness being 7.5 to 8. They are somewhat inferior, therefore, to such
gems as topaz, sapphire, and ruby in wearing qualities, although hard
enough for ordinary purposes.
The specific gravity of beryl is also about like that of quartz,
ranging from 2.63 to 2.80. It is, therefore, relatively light as com-
pared with other gems. Beryl is practically infusible, and is not attacked
Beryl crystallizes in the hexagonal system. It usually occurs as
six-sided prisms, commonly terminated by a single flat plane, but some-
times by numerous small planes, giving a rounded effect, and occasion-
ally by pyramidal planes, which cause the prism to taper to a sharp
The crystals sometimes grow to enormous size, exceeding those
of any other known mineral. Thus, one found in Grafton, New Hamp-
shire, was four and one-quarter feet in length, and weighed two thou-
sand nine hundred pounds. Another in the same locality is estimated
to weigh two and one-half tons. In the Museum of the Boston Society
I Golden Beryl (Siberia).
Blue Beryl (Siberia).
3 Blue Bervl 'Albany, Maine).
4- Aquamarine (Conn.)
' Golden Beryl (Conn.)
copymsHT ioi, sr . w. MUMFOHO,
lp Aquamarine (Ural Mountains).
"I ^nit-raid i" matrix (Ural Mountains)
Crystal forms of beryl
of Natural History, and in the United States National Museum, are
exhibited single crystals also of great size. That in Boston is three
and one-half feet long by three feet wide, and weighs several tons.
That in the National Muse-
um weighs over six hundred
None of these crystals is
of a high degree of purity or
transparency, but the crystal
planes, at least of the prisms,
are well developed.
Beryl crystals have no
marked cleavage, except a slight one parallel with the base. Where
broken, the surface shows conchoidal fracture.
The mineral is quite brittle. Some emeralds even have the annoy-
ing habit of breaking of their own accord soon after removal from
the mine. This can be prevented by warming them gradually before
exposing them to the heat of the sun, or other sudden heat.
Beryl and its varieties are dichroic ; i. e., the stones exhibit different
colors when viewed in different directions. This dichroism can some-
times be observed by the naked eye, but better with the dichroscope.
With this instrument the twin colors seen are, for the emerald, yellowish
green and bluish-green; for the aquamarine, straw-white and gray-
blue; and for noble beryl, sea-green and azure. The dichroism when
seen furnishes a positive means of distinguishing a true stone from any
The varieties of beryl have not the brilliancy of the diamond, the
double refraction being weak and the dispersion small. They therefore
depend on their body colors and their luster for their beauty and attrac-
tiveness. Fortunately they usually exhibit these qualities as well by
artificial light as by daylight.
Ordinary beryl is a mineral of comparatively common occurrence,
being often found in granitic and metamorphic rocks, although that of
common occurrence is usually too 'clouded and fractured to be of use for
gem-cutting. There are many localities, however, where beryls of gem
Of the different varieties of beryl, the emerald is by far the most
important as a gem. Its pure green color, unalloyed by a single ray
of yellow, has ever made it an object to be sought for with avidity,
and it will probably always be the standard green gem.
The finest emeralds in the world come from Muso, a locality in the
United States of Colombia, seventy-five miles north-northwest of Bogota.
It is a somewhat inaccessible region, and the mining of the gems is
a precarious occupation. The emeralds occur in a dark, bituminous lime-
stone, which is shown by fossils to be of Cretaceous age. As emeralds
in other localities occur only in eruptive or metamorphic rocks, it seems
possible that the Muso emeralds have washed in from an older forma-
tion. The emerald-bearing beds are horizontal, overlying red sandstone
and clay slate. Calcite, quartz, pyrite, and the rare mineral parisite are
other minerals found associated with the emerald. The manner of work-
ing these emerald mines is thus described by Streeter :
"The mine is worked by a company, who pay an annual rent for
it to the government, and employ one hundred and twenty workmen.
It has the form of a tunnel, of about one hundred yards deep, with
very inclined walls. On the summit of the mountains, and quite near
to the mouth of the mine, are large lakes, whose waters are shut
off by means of water-gates, which can be easily shifted when the
laborers require water. When the waters are freed they rush with
great rapidity down the walls of the mine, and on reaching the bottom
of it they are conducted by means of an underground canal through
the mountain into a basin. To obtain the emeralds the workmen begin
by cutting steps on the inclined walls of the mine, in order to make
firm resting-places for their feet. The overseer places the men at cer-
tain distances from each other to cut out wide steps with the help
of pickaxes. The loosened stones fall by their own weight to the
bottom of the mine. When this begins to fill, a sign is given to let
the waters loose, which rush down with great vehemence, carrying the
fragments of rock with them through the mountain into the basin.
This operation is repeated until the horizontal beds are exposed in
which the emeralds are found."
The mines are owned by the government, by whom they are leased
for terms of seven to fifteen years to the highest bidder. The working
of the mines has been almost continuous since 1558, and they have been
the principal source of emeralds obtained in modern times. Emeralds
also occur in small numbers throughout the black aluminous schists
of the Eastern Cordilleras of Colombia. A few are thus obtained from
Cozenez, Somondose, Nemocon, etc. They are not mined systematically
except at Cozenez.
The next most prominent locality whence gem emeralds are obtained
is in Siberia, on the river Takovaya, forty-five miles east of Ekaterinburg.
The emeralds here found are often larger than any yet obtained in
South America, but they are not of so good quality. They occur in
mica schist (see colored plate), and often associated with phenacite,
chrysoberyl, rutile, etc.
Other localities whence emeralds are obtained are Upper Egypt
(the source of those known to the ancients) ; the Heubachthal in
Austria; and Alexander County, North Carolina, in our own country.
The latter locality has afforded a number of fine crystals, and work
at the mines has recently been renewed.
The form of cutting given the emerald depends upon the shape of
the rough stone. The table cut like that of the emerald shown in the
frontispiece to this work is perhaps the most common. The step cut is
also employed, and brilliants and rose cuts are occasionally made.
Emeralds seem to have been known and prized from the earliest
times. They are mentioned in the Bible in several places, and their use
in Egypt dates back to an unrecorded past, for they frequently appear
in the ornaments found upon mummies. Readers of Roman history
will remember that the EmperoikNero used an emerald constantly as an
eye-glass, though whether this was a real emerald may be questioned.
The Incas, Aztecs, and other highly civilized peoples of South America
were reported to have used these gems profusely for purposes of adorn-
ment and for votive-offerings. It was partly the desire to secure emeralds
which led Cortez and his followers, early in the sixteenth century, to
undertake the conquest of Peru. Some of the emeralds thus obtained
from the Incas by Cortez and brought to Spain were said to have
been marvels of the lapidary's art. One was carved into the form
of a rose, another that of a fish with golden eyes, and another that
of a bell with a pearl for a clapper. During the years following Cortez'
conquest large quantities of the so-called emeralds were brought to Europe.
Joseph d'Acosta, a traveler of the period, says the ship in which he
returned from America to Spain carried two chests, each of which con-
tained one hundred pounds' weight of fine emeralds. It is probably,
however, quite incorrect to regard the stones as true emeralds. They
were more likely jade or some other green stone to which the name
emerald was applied. The true emerald is too brittle to be easily en-
graved, and it is not likely that any such large quantity as reported
was ever found of this stone. Working of the Colombian mines was
begun by the Spaniards in 1558, and there has been practically no
interruption in their operation since that time.
The ancients had many superstitions regarding the emerald, one
being that it had a power to cure diseases of the eye. Engravers of gems
and other artificers were accustomed, therefore, to keep an emerald in
front of them while at work, believing it would rest their eyes to look
upon it occasionally, and that the water in which the stone stood would
cure inflammation of those organs. Another notion was that the emerald
would reveal the inconstancy of lovers by changing color.
"It is a gem that hath the power to show
If plighted lovers keep their troth or no;
If faithful, it is like the leaves of spring;
If faithless, like those leaves when withering."
Another belief was that the emerald would blind the eyes of the ser-
pent, a fancy referred to in Moore's lines :
"Blinded like serpents when they gaze
Upon the emerald's virgin blaze."
The emerald was also the symbol of immortality and of conquered
sin and trial. It was believed that emeralds came from the home of the
griffin, and that to obtain them thence exposed the miner to great danger.
As late as the seventeenth century powdered emerald was widely
used as a drug, being regarded when taken internally as a powerful
remedy for dysentery, epilepsy, venomous bites, and fevers.
Like all other gems, the value of emeralds varies much according
to their perfection. Those of the best grade are worth from $100 to
$1,000 a carat. The passion for emeralds at the present time, together
with the fact that very few are being found, makes them among the
most costly of gems. A three-carat emerald recently sold for $875,
and a six-carat stone for $4,000. A six-carat diamond might not be
worth over $1,000 at present. The color should be a dark velvety
green, those of lighter shades being much less valuable. Owing to the
extreme brittleness of the mineral, emeralds usually contain flaws, so
that " an emerald without a flaw " has passed into a proverb to indicate
a thing almost unattainable.
The largest and most beautiful emerald known to be in existence
at the present time is one owned by the Duke of Devonshire. This
is an uncut, six-sided crystal, about two inches long, and of the same
diameter. It is of perfect color, almost flawless, and quite transparent.
Aquamarines and other beryls are found in Siberia, India, Brazil,
and in many localities in the United States. Pieces suitable for cutting
are quite frequently found, and the cut stones are much lower in price
tnan the emerald. Large stones are frequently obtained. Dana mentions
an aquamarine from Brazil which approaches in size, and also in form,
the head of a calf. It weighs 225 ounces troy, is transparent, and
without a flaw. In the Field Columbian Museum is to be seen a beau-
tiful cut aquamarine from Siberia more than two inches in diameter,
which weighs 331 carats. Here is also the finest specimen of blue
beryl ever cut in the United States. It was found in Stoneham, Maine,
is rich sea-green color in one direction and sea-blue in another. It
weighs 133 carats. Numerous other Maine localities have furnished
gem beryls. Golden beryls are found in Maine, Connecticut, North Caro-
lina, Pennsylvania, and other United States localities, as well as in Siberia
and Ceylon. From them are obtained gems of rich golden color resem-
bling topaz or citrine.
Beryl of a pale rose color is sometimes found, and when of good
quality is cut for gem purposes, but it is of too rare occurrence to be
important. A variety of beryl containing two to three per cent of the
metal caesium is found at Hebron, Maine, which affords transparent,
colorless stones of a brilliant luster.
Aquamarine and other varieties of beryl seem not to have been
as highly esteemed as emerald by the ancients, although beryl is men-
tioned in the Bible, and early writers describe gems evidently belong-
ing to the species. A notable biblical mention is that found in the
Song of Solomon, where it is said:
"0 daughters of Jerusalem,
This is my beloved and this is my friend,
His hands are as gold rings set with the beryl."
The beryl was believed, in the Middle Ages, to give its wearer insight,
second sight, and foresight, to induce sleep and compose the heart and
mind. It was called " the sweet-tempered stone." It was especially
used in the seventeenth century for divination, the method being to
suspend a ring containing a beryl in a bowl filled with water. The edges
of the bowl being marked with the letters of the alphabet, the beryl gave
answers to questions asked by stopping before certain letters. It was
also supposed to possess special power over evil spirits, and it was said
that a man might call a devil out of hell and receive answers to such
questions as he might ask if he but held a beryl in his mouth. The
globe in the English crown is surmounted by a blue beryl, in allusion
perhaps to the supposed magical power of the stone.
Euclase is a rare mineral, resembling beryl in color and hardness,
and like it a silicate of glucina and alumina. It differs from beryl,
however, in containing water in its composition, in being monoclinic
in crystallization, and in having higher specific gravity. The percen-
tage composition of euclase is: Silica 41.3, alumina 35.2, glucina 17.3,
and water 6.2. Its specific gravity is 3.05-3.10. It barely fuses before
the blowpipe, and is not attacked by acids. It has a vitreous luster,
which becomes more brilliant on polishing a surface. The cut stones
are made from transparent crystals, which range from colorless to blue
and green, the latter resembling Russian topaz and aquamarine. Brazil
and the Ural Mountains furnish practically all the euclase thus far
known, and this in but small quantity. The Brazilian euclase is found
at Boa Vista, in the province of Minas Geraes, in the same locality
with yellow topaz. It occurs in nests in quartz veins which penetrate
the schists of the region. The crystals found in the Urals are larger,
one three inches in length being known. ^Euclase is also found in the
auriferous gravels of the Sanarka River in the Government of Orenburg,
Russia, chrysoberyl and topaz being accompanying minerals. Euclase
possesses a strong cleavage, which gives it its name, and makes it some-
what difficult to cut. On account of the rarity of the mineral good
stones command a high price.
Phenacite affords transparent, colorless gems of a brilliant vitreous
luster. They are usually cut as brilliants, and stand between the dia-
mond on the one hand and rock crystal on the other in the amount of
u fire" they display. Phenacite has stronger double refraction than
quartz, and a higher index of refraction. It is far, however, from
equaling the diamond in these properties. In fact, it resembles quartz
so much that it was not until 1833 recognized as a distinct species.
The name of phenacite, from the Greek phenax, a deceiver, was given
to it because of this resemblance. Like beryl and euclase, pheuacite
is a silicate of glucinum. Its percentage composition is, silica 54.45,
glucina 45.55. It is infusible before the blowpipe, and can be distin-
guished chemically from quartz by putting a drop of cobalt nitrate on a
heated fragment and then reheating. The fragment turns blue if phena-
cite ; if quartz it remains black. Phenacite is harder and slightly heavier
than quartz, its hardness being 7.5-8, and its specific gravity 2.97-3. It
crystallizes in the rhombohedral division of the hexagonal system. The
gems are usually obtained from crystals.
Phenacite is not a common mineral, and nearly all that has been cut
for gems has come from two localities, '^Takovaya, near Ekaterinburg,
Russia, and Mt. Antero, Chaffee County, Colorado. The first locality
furnishes the finest and largest stones, some of them weighing thirty to
forty carats. They occur together with emerald and chrysoberyl in
mica schist. The Mt. Antero phenacite is found at an elevation of 14,000
feet, and is obtainable for only a short period during the summer on
account of the abundant snows of the region. This locality affords
smaller gems than the Russian, and owing to the demand for them as
mineralogical specimens, few are cut. They usually occur implanted
on quartz, beryl, or feldspar. Some good phenacite has been found
on Bald Mountain, near North Chatham, New Hampshire, in a granite
vein and near Florissant, Colorado. Besides being colorless, phenacite
may exhibit pale rose and wine-yellow colors.
This mineral is like beryl in containing the element glucinum
(beryllium), but in other respects is a distinct species. Chrysoberyl has
no silica in its composition, as has beryl, but is composed of glucina
and alumina, the theoretical percentages being glucina 19.8, alumina
80.2. In nature, however, some other oxides are usually present as
impurities or replacing the alumina. Such are iron and chromium
oxides. Chrysoberyl is remarkable for its hardness, this being 8.5, and
thus near that of corundum. The cut stones therefore retain a polish
well. The specific gravity of the mineral is somewhat greater than that
of the diamond, being 3.5 to 3.8. It crystallizes in the orthorhombic
system, and often forms twins which are so united as to make a six-
rayed stellate crystal, or six-sided prisms. An illustration of one of these
crystals may be seen in the colored plate. Chrysoberyl has a prismatic
cleavage and conchoidal fracture. Its luster is vitreous, tending to oily,
and is brilliant. The mineral is infusible, and is not attacked by acids.
In color it usually presents some shade of green, tending at times to
brown or yellow. The name chrysoberyl means literally golden beryl,
and suggests a yellow stone. While this is a common color, grass-green
and erne raid -green are frequent and characteristic. Among jewelers
chrysoberyl, especially the Brazilian chrysoberyl, is often known as
chrysolite, a custom which has doubtless arisen through the similarity
in color of the two minerals. Three kinds of chrysoberyl are employed
in jewelry, and being given different names may be considered separately.
These are : (1) ordinary chrysoberyl, (2) cymophane, or cat's-eye, and (3)
alexandrite. Ordinary chrysoberyl, also called Oriental chrysolite, or
chrysolite, is greenish-yellow to smoky-brown in color, and is employed
as a gem only when transparent. It is for the most part obtained in
Brazil and Ceylon, in the gem gravels of both of which countries it occurs.
The Brazilian chrysoberyls are rolled pebbles, scarcely larger than beans,
and occur together with topaz, garnet, tourmaline, quartz, etc., in the beds
of streams chiefly in the northern part of the province of Minas Geraes.
The stones occur in the neighborhood of granite and gneiss, and were
therefore probably originally formed in these rocks. The (Ceylonese
chrysoberyls are likewise found in stream beds, and come from Sa^ra-
gam and the neighborhood of Matura in the southern part of the island.
In North America, chrysoberyl has been found in Maine, Connecticut, and
North Carolina, but few stones sufficiently transparent for cutting occur.
Cymophane, or "cat's-eye," is a name given to a translucent, opalescent
variety of chrysoberyl, across a polished surface of which may be seen
to play a single long, narrow ray of light, changing position with every
movement of the stone. The phenomenon is like that exhibited by star
sapphires, except tiiat but a single ray is seen instead of several. The
cause of the appearance is believed to be multitudes of minute tube-like
cavities in the stone arranged in parallel position, which reflect the light
which falls upon them. In cutting the stone the best effect is produced
by giving it the form of a long oval, over the middle of which a light
ray runs and produces a resemblance to the eye of a cat. Such stones
are the true "cat's-eyes" of jewelry, the quartz cat's-eye being much
inferior. The name cymophane, also applied to these stones, comes from
two Greek words, meaning wavy appearance. The cat's-eye variety of
chrysoberyl occurs together with the transparent kind above described
in the alluvial deposits of Ceylon and Brazil. The stones are not large,
rarely exceeding 100 carats in weight. The largest and finest known is
in the South Kensington Museum of England, and is about an inch and
a half in length and of the same thickness.
In Oriental countries the cat's-eye has long been highly esteemed a
preserver of good fortune, the belief being that each stone is inhabited
Iby a good spirit. It is believed to be a guardian of its owner's wealth
and to protect him from poverty. The stone is often carved by Orientals
into the form of some animal's head, thus increasing its weird and
mysterious aspect. The popularity of the stone among Europeans was
suddenly increased a few years ago when the^Duke of Connaught gave
one in a betrothal ring to his bride, Princess Margaret of Prussia. Cat's-
eye immediately became the fashion among the wealthy classes, and the
supply proved quite unequal to the demand. The stone is still quite
fashionable, and not less than one hundred dollars per carat must often
be paid to secure a good one.
Alexandrite is a variety of chrysoberyl found in the Ural Mountains,
and received its name from the fact that it was first found on the birth-
day of Alexander II., Czar of Russia, in the year 1830. Moreover, the
colors which it presents, green and red, are the national colors of Russia.
Alexandrite by ordinary light is dark grass-green, or emerald-green, in
color, but on holding it to the sunlight, or viewing it by artificial light,
it appears columbine-red. The gem has therefore the unique property
of appearing as "an emerald by day and amethyst by night." The
locality where alexandrite was originally found, and where most of it
has been obtained, is ^akovaya, near Ekaterinburg. Only the trans-
parent pieces can be used for gems, and as these are relatively scarce,
the price of the gem is high. Of late alexandrite has been found in
the gold sands of Sanurka in the southern Urals, but a more impor-
tant source of supply has appeared in Ceylon, where gems much
larger than those in the Urals, and in a fine variety of colors, have
Zircon is a mineral remarkable among those employed as gems for its
high specific gravity and adamantine luster. For these reasons the color-
less, transparent stones are sometimes employed as substitutes for the dia-
mond, although they lack the high refractive power and hence play of colors
of the latter. The stones are sometimes called "Matura diamonds,"
because of their abundance at Matura in the island of Ceylon. The color-
less, or smoky zircons, are often known as " jargons " or " jargoons,"
a name said to have been given in allusion to the fact that though
they resembled the diamond in luster they had really much less
value. Besides zircons of this sort there are those known in jewelry
as " hyacinth " or " jacinth," which are transparent zircons of a brown-
ish, red-orange color. A stone of a nearly similar color is furnished
by the essonite variety of garnet, and this is also often known as
The high specific gravity of zircon above referred to is more than
four times the weight of water, determinations giving results varying
between 4.2 and 4.86. Zircon is thus the heaviest of gems, and will
sink at once in any of the ordinary heavy liquids. The hardness
of zircon is between that of quartz and topaz, being 7. Its index
of refraction is high, being 1.92, or near to the diamond among gems,
a fact which accounts for its brilliancy when cut. Before the blowpipe
zircon is infusible. It is not acted upon by acids except in fine powder
by sulphuric acid. In composition it is a silicate of zirconium, the per-
centages being silica 32.8, zirconia 67.2. It usually also contains a little
iron oxide. It is not an uncommon mineral in rocks, occurring in
crystals of microscopic size, and in crystalline rocks it sometimes
occurs in large and abundant crystals. These are usually opaque and
of no value for gem purposes, although they are mined to some extent at
the present time for use in incandescent lights. Opaque zircon is found
in this country in Georgia, Colorado, New York, and Canada. The
form of the crystals is usually that of four-sided prisms terminated
by pyramids. The transparent zircons available for gems, that is, the
so-called " noble " zircons, come almost wholly from the island of Ceylon,
where they occur in the gem gravels that contain also rubies, sapphires,
garnets, tourmalines, etc. The zircons are in the form of rolled pebbles,
rarely of large size, few stones of over ten or twelve carats weight
being found. In other localities some noble zircons are found in pan-
ning for gold, the high specific gravity of the zircon causing it to stay
in the pans almost as long as the gold. Along the Espailly River,
in Auvergne, France, are found zircons which yield brilliant though
small stones of the true jacinth color. Neither in the form of hyacinth,
or jargoon, is zircon at the present time very extensively used in jewelry,
although it has many of the qualities desirable for gems. The best
stones are rarely valued now at more than ten dollars per carat,
although they were once highly prized. One peculiarity of zircon
that should be noted
is the change of its
color which some-
times takes place on
long exposure to
light, the color
sometimes thus dis-
er. It is usually,
also, driven out by
heating. As it has
been found that the mineral when heated away from oxygen does not
lose or change its color, the conclusion is drawn by some that the
color depends on the state of oxidation of contained iron; but others
think it of organic origin. The red varieties of zircon are sometimes
sold for rubies, but they may be easily distinguished from true rubies by
their lower hardness and higher specific gravity. Zircon becomes phos-
phorescent but not electric upon heating.
The ancients employed a stone which they knew as hyacinth; but
its color was bluish, and hence it is generally supposed to have been
our sapphire or amethyst. The lyncurion of Theophrastus is more likely
to have been our zircon, the ancients having employed it for making
signets, some of which are still preserved. In the Middle Ages hyacinth
was supposed to have the power of procuring sleep, riches, honor, and
wisdom, and of driving away plagues and evil spirits. Cardanus, writing
in the sixteenth century, says that he was accustomed to carry a hya-
cinth (jacinth) about with him for the purpose of inducing sleep, which
" it did seem somewhat to confer, but not much."
Forms of zircon crystals
Green Tourmaline (Brazil).
Green Tourmaline (Haddam, Conn.)
Cross Section of Green Tourmaline (Cal.)
Red Tourmaline or Rubellite (Island of Elba).
Brown Tourmaline (Gouverneur, K. Yj
Red Tourmaline or RuUellite, in Lepidolite (Cal.)
COPymiMT 1(03, IV A. W. MUMFOHO, CHNMO.
Black Tourmaline (Finland).
Early in the eighteenth century some children of Holland, playing
on a warm summer's day in a courtyard with a few bright colored
stones, noticed that these possessed a strange power when warmed by
the heat of the sun. They attracted and held ashes and straws. On
reporting this strange discovery to their parents the latter, it is said,
could give no explanation of the curious property, but left a record
of their knowledge of it in the name of " aschentreckers," or "ash-
drawers," which they gave the stones, and by which they were known
for a long time.
This was the method of introduction to the civilized world of the
mineral now known as tourmaline, a mineral which in variety of color,
composition, and properties is of considerable interest in Nature.
The lapidaries who had given the Dutch children the stones for play-
things did not recognize them as different from the other gems with which
they were accustomed to deal. So to the present day, although tour-
maline is considerably used in jewelry, it is rarely ever called by that
name. The green varieties are often known as Brazilian emerald, chrys-
olite, or peridot, some varieties of blue as Brazilian sapphire, others as
indicolite, the colorless as achroite, and the red as rubellite, siberite, and
even as ruby.
It is only somewhat recently that these different stones have been
recognized as being varieties of a single mineral species which is known
by the name tourmaline. This name comes from a Cingalese word
(turamali), which was applied to the first tourmaline gems sent from
Ceylon to Holland.
At one time the name schorl was chiefly applied to the species. This
was before the means of distinguishing mineral species were as well
understood as they are now, and a large number of minerals, and even
rocks, were included under the name schorl. One by one, however, they
were distinguished by separate names until schorl included only tourma-
line, and shortly afterward the name schorl was dropped altogether.
In its opaque form, colored either black or brown, tourmaline is a
comparatively common mineral. It accompanies many so-called meta-
morphic rocks, and is also common in granite and other eruptive rocks.
As a rock-forming mineral it often occurs as long, slender prisms, fre-
quently about the size of a darning-needle, and radiating in all directions.
The only mineral for which it is likely to be mistaken in this form is
hornblende. It can be distinguished from this in the following manner :
On fusing the powdered mineral with a mixture of bisulphate of potash
and fluor-spar (best done on a little loop of platinum wire) tourmaline
will color the flame green, while hornblende will produce no coloration.
The black opaque crystals of tourmaline often reach a large size, some
being known four feet in length. Both black and brown tourmaline are
usually opaque, and hence have no value as gems. Tourmaline of other
colors, however, is often transparent, and this is of gem value.
The gem tourmalines are to be found in only a few localities. They
occur in Maine, Connecticut, and California in our own country, and
also in Brazil, Russia, and Ceylon. The crystals are usually in the
form of long, slender prisms, often having the peculiarity of being differ-
ently colored in different portions. Thus a crystal may be green at
one end and red at the other, and in cross-section may show a blue
center, then a colorless zone, then one of red, and then one of green.
Some of the crystals from Paris, Maine, change from white at one termi-
nation to emerald green, then light green, then pink, and finally are
colorless at the other termination. In some crystals again the red passes
to blue, the blue to green, and the green to black.
Exactly what produces these differences of color is not known. It is
known that black tourmaline has an excess of iron, the red and green an
excess of sodium and lithium, and the yellow and brown an excess of
magnesium in their composition. These same differences of composition
characterize similar colors in portions of the same crystal as well as
separate crystals. Hence the evidence is quite conclusive that the color
in some way depends on the composition. Many transparent tourma-
lines, while appearing of a uniform color when viewed in any one
direction, exhibit different colors when viewed in different directions.
Thus, one of the long, slender crystals may appear green when held
lengthwise in front of the eye, but when looked at from the end appears
brown. Again, some crystals appear perfectly transparent when viewed
perpendicularly to the sides of the prism, but when viewed from the end
are nearly opaque. This may be true even when the thickness is less
in the latter direction. Both these properties are due to the arrange-
ment of the molecules of tourmaline, which is such as to make the power
of absorbing light different in different directions.
The form of crystals of tourmaline is usually that of a three-sided
prism. The sides of the prism are usually marked by narrow parallel
lines called striae, and the prism may be more or less rounded by the
addition of other planes.
If a doubly terminated crystal be examined carefully, it will be
seen that the planes on the two ends are not alike, either in number or
inclination. On one end there may be three planes, on the other six,
or even twelve. If the planes on one end make a blunt termination,
those on the other may make a sharply pointed one. Such a peculiarity
of crystal form is possessed by but few minerals. Those possessing it
are said to be hemimorphic, i. e., half formed. Some minerals, among
which is tourmaline, which exhibit this peculiarity of form are often
also pyroelectric, i. e., become electric on heating. It was this devel-
opment of electricity which caused the stones with which the Dutch
children played, to pick up ashes, etc., when the stones were warmed
by the heat of the sun. Any one can repeat their observation by
gently heating crystals, or even fragments of tourmaline, and applying
them to bits of paper. The electrical attraction will often be found to
be very strong, though it varies with different crystals. The fragments
should not be overheated, the electricity being most strongly developed
between 100 and 200 Fahrenheit.
In composition tourmaline is a complex silicate, chiefly of aluminum
. and boron. Iron, magnesium, the alkalies, and water also enter in vary-
ing amounts into it. In fact, so complicated is its chemical nature that
perhaps no other mineral has been so often analyzed or had its analyses
so much discussed.
Ruskin, in his "Ethics of the Dust," thus describes the composition
of tourmaline : "A little of everything; there's always flint and clay and
magnesia in it ; and the black is iron according to its fancy; and there's
boracic acid, if you know what that is, and if you don't, I cannot tell you
to-day, and it doesn't signify ; and there's potash and soda ; and on the
whole, the chemistry of it is more like a mediaeval doctor's prescription
than the making of a respectable mineral."
Tourmaline is both harder and heavier than quartz, its hardness
being 7-7.5, and its specific gravity 2.98-3.20. It is thus sufficiently
hard for use as a gem. It is, however, quite brittle, and even at times
friable. Cracks therefore frequently cut across good crystals, and spoil
what would otherwise make a good gem. It is very common to find
tourmalines in the rocks broken into a number of pieces, and the frag-
ments "mended " together with quartz or calcite. This has been true of
the black tourmaline shown in the accompanying plate. Scarcely any other
mineral exhibits this change so often as tourmaline, a result due probably
to its brittleness and the character of the rock in which it occurs.
The strong dichroism of tourmaline should be borne in mind in cut-
ting gems from it. Since a crystal looked at in the direction of the
vertical axis is usually much less transparent and of less pleasing color
than when seen at right angles to this direction, gems should be cut with
the table parallel to the prism. They will then exhibit their most pleas-
ing color in the direction in which they are usually seen.
Of the different colors of tourmaline used for gems, red shades are
less abundant, and more highly prized than green. Of the red tourma-
lines, those dark red are most valued, especially if, as is sometimes the case,
a color like that of the ruby is exhibited. A rose-red color is, however,
more common. The green tourmalines are usually dark green, shading
to blue or yellow, and almost never exhibit the true emerald-green. Blue
tourmalines are least abundant of any, and are rarely cut. Their color is
usually an indigo-blue. Tourmaline is not attacked by acids, and the
transparent varieties are infusible. Partly on account of its lack of
strong color, and partly because it is not better known, tourmaline has
not hitherto obtained much popularity as a gem, although its hardness,
dichroism, and transparency are such as to warrant its more extensive use.
Recently, however, it has obtained more favor, and the supply of
Brazilian tourmalines especially is hardly equal to the demand.
One of the best known localities for gem tourmalines is Paris, Maine.
It was discovered by two boys, by name Elijah L. Hamlin and Ezekiel
Holmes. They were interested in the study of minerals, and spent much
of their leisure time searching for them. One day in the fall of 1820,
having been out many hours hunting for minerals, they were about to
return home when a gleam of something green at the roots of a tree
caught their eye. Eagerly bringing it to light, they found it to be a
beautiful green tourmaline. A fall of snow that night prevented their
obtaining more of the crystals, but the following spring they returned
and secured many fine gems. The locality has been extensively worked
since then, and has furnished many fine gems, which have gone to adorn
the coronets of kings and enriched the mineral cabinets of the world.
The tourmaline occurs in pockets in pegmatitic granite. Black tour-
maline, muscovite, and lepidolite are of constant occurrence through the
granite. The granite is overlaid by mica schist, which at present is
being stripped off to permit of further mining. It is estimated that fifty
thousand dollars' worth of tourmalines have been taken from this one
locality. Auburn and Rumford, Maine, are two other neighboring locali-
ties where good gems have been found. At Haddam Neck, Connecticut,
fine transparent tourmalines occur, generally green in color, and many
of them of gem quality. They occur in granite.
Tourmaline mine, Mt. Mica, Paris, Maine
Tourmaline mine, Haddam, Conn.
The red tourmaline (rubellite) from California, illustrated in the
accompanying colored plate, is found in San Diego County of that State.
The matrix in which it occurs is a lithia-bearing mica ( lepidolite ) of a
delicate violet color. In this matrix the tourmaline usually occurs in
radiating masses. The rose color of the tourmaline contrasting with
the violet of the lepidolite makes an object which is quite a favorite
with mineral fanciers, although the former is not sufficiently transparent
to be used as a gem. At two other localities in the same State large
transparent tourmalines of varying colors have been found.
Tourmaline is found frequently in Brazil in the gem gravels, accom-
panying topaz, amethyst, diamond, etc. It is mostly green in color,
and is known as Brazilian emerald, it having been for a time mistaken
('In the Ural Mountains, near Ekaterinburg, crystallized tourmaline
occurs in cavities in granite, accompanying amethyst, beryl, topaz, etc.
These crystals often have a fine dark red color, and produce the gems
known as Siberian rubies. They are especially prized in Russia.
\ A.lthough the name tourmaline came from Ceylon, the gem there
known by that name is hyacinth. True tourmaline occurs, however, on
the island in the gem gravels. This is usually of a yellowish-green color,
and is often known as Ceylonese chrysolite. |
On the Island of Elba are also obtained tourmalines, generally red
in color, transparent, and well crystallized. They are, however, not
extensively used as gems, on account of their small size.
This variety of mica is attractive on account of its pink or lilac
color. It usually occurs in scaly, granular masses, which often have
sufficient coherence to admit of carving them into various ornamental
objects, such as paper-weights, small vases, and boxes. They are some-
what easily scratched, since the hardness of lepidolite is only 2.5-4. Lepi-
dolite is often known as lithia mica, on account of its content of lithium,
four per cent to five per cent. This affords a criterion for the determi-
nation of the mineral, as a fragment heated before the blowpipe gives
the purple-red flame of lithia.
/The principal European deposit of lepidolite which has been used
for ornamental purposes, is that at Rozena, in Moravia, where a quantity
of the mineral of an especially pleasing rose-lilac color occurs. In the
United States, lepidolite occurs at Paris, Rumford, and several other
points in Oxford County, Maine, and in California, eight miles from
San Diego. The deposit at the latter place is an extensive one, and
is mined for lithia salts. This lepidolite is penetrated by crystals of rubel-
lite, giving an effect as shown in the colored plate. Although some of the
American lepidolite is nearly equal to the European in quality of color,
no use seems as yet to have been made of it for ornamental purposes.
Spodumene is the only one of the gem minerals except tourmaline
and lepidolite, which contains the element lithium in any large amount.
It is a silicate of alumina and lithia, having the percentages, silica 64.5,
alumina 27.4, and lithia 8.4. It fuses rather easily before the blowpipe,
and gives the purple-red color of lithia to the flame, making a con-
venient means of distinguishing the species. Its hardness is 6.5-7, and
specific gravity 3.1-3.2. Its luster is vitreous. Ordinarily it is opaque,
and of a white or gray color, the word spodumene being derived from
the Greek spodios, meaning ash-colored.
Spodumene crystallizes in the monoclinic system, often forming large
crystals up to four feet in length. The use of spodumene as a gem
is confined almost exclusively to a transparent emerald-green variety
occurring in North Carolina, and a yellow variety, also transparent,
obtained in Brazil. The emerald-green spodumene is known as hidden-
ite, after W. E. Hidden, who first developed it. It occurs in thin, bladed
crystals, varying from colorless through yellow to an emerald-green
color. These afford only small gems, none over five carats being obtain- ^
able. A high price has been obtained for these, ranging between
forty dollars and one hundred dollars per carat. They are cut into
step or table stones, as this best exhibits their dichroism, and avoids
the danger of splitting from the marked prismatic cleavage present.
All the hiddenite thus far known has been obtained at Stony Point,
Alexander County, North Carolina, and this locality is now exhausted.
The yellow spodumene, above referred to as obtained in Brazil, was
long thought to be chrysoberyl. Its distinction from chrysoberyl, by the
properties above mentioned, is easy, although its use in jewelry is simi-
lar. Pieces of spodumene, of a beautiful blue color, are also occasion-
ally found near Diamantina, in Brazil. Quite recently spodumene has
been found near Pala, San Diego County, California, in the form of large
transparent crystals of an amethystine hue. These afford large, hand-
some gems, resembling amethyst in color, but distinguished from it by
their dichroism and their rose to lilac shades. The name of kunzite has
been applied to this variety of spodumene.
Topaz with Mica and Feldspar (Russia),
Topaz in Rhyolite (Utah).
Waterworn Topaz (Brazil).
Remarkable clearness and transparency, capacity of taking a high
polish, and hardness and weight greater than that of quartz are the
qualities in which topaz excels as a gem. Numerous other stones
of inferior quality masquerade under its name, however, and this fact
may account for the decline in popularity which the stone has suffered
in recent years. True topaz is a silicate of alumina, containing hydroxyl
and fluorine. Its hardness is 8, and it thus scratches quartz. Topaz
is also remarkably heavy, considering its composition, it being three
and one-half times as heavy as water. Owing to this unusual specific
gravity, those accustomed to handling gems can frequently pick out
the topaz from a miscellaneous lot of precious stones without remov-
ing their wrappings.
/ ^The color typically associated with topaz in its use as a gem is yellow.
Yet the mineral species exhibits many other shades of color, which, when
present in crystals of sufficient clearness and purity, answer equally
well for gem purposes. These other shades, most of which are repre-
sented in the accompanying plate, are grayish, greenish, bluish, and
reddish. Topaz may also be quite colorless. The yellow color of the
Brazilian topaz can be changed by heating to a pale rose-pink, and
the gem is often treated in this way. The degree of heat employed
is not high, and both heating and cooling must be performed gradu-
ally. The selected stone may be packed in magnesia, asbestos, or lime,
and heated to a low, red heat, or it may be wrapped in German tinder
and the latter set on fire. Only stones of a brown-yellow color yield
the pink ; the pale yellow stones turn white when so treated. Once the
pink color is obtained it is permanent. The natural colors of topaz
are in general perfectly durable, although some of the deep wine-yellow
topazes from Russia fade on exposure to daylight./
Topaz is infusible before the blowpipe. It is not affected by hydro-
chloric acid; but is partially decomposed by sulphuric acid, and then
yields hydrofluoric acid. If the latter experiment is tried in a closed
glass tube, the formation of the hydrofluoric acid is made evident by
the etching and clouding of the walls of the tube. The powdered stone
should be mixed with acid sulphate of potash for this experiment.
Forms of topaz crystals
Another test for topaz is to heat the powdered mineral with cobalt
nitrate, when it assumes a fine blue color, due to the alumina
which it contains.
The crystals of topaz belong to the orthorhombic system of crystal-
lization. They are usually elongated in the direction of the prism, and
have sharp, bright faces. They vary much in size, and often are large.
One crystal weighing twenty-five pounds was found in Siberia. Large
gems of topaz are, therefore, quite easily obtained. Perhaps the largest
cut topaz known was recently presented to Pope Leo on the occasion
of his silver jubilee (1902).
This stone weighed nearly
four pounds. It was obtained
originally in Brazil.
A well-marked character-
istic of all topaz crystals is
their tendency to cleave
across the prism parallel with
its base. Such a cleavage
plane can be seen cutting across the crystal shown in the upper right-
hand corner of the accompanying plate. This cleavage is so marked, and
the cleavage plane so bright and flat, that in cutting topaz for a gem
a cleavage surface is used as the upper face of the gem, and the other
faces formed around it. Owing to this easy cleavage the owner of a cut
topaz should be careful not to let the stone drop, as it might be thus
cracked or broken. Topaz takes a high polish, and colorless gems
of the mineral resemble the diamond considerably. They are, however,
softer, and have weak double refractive and dispersive power.
txThe name topaz is derived from the Greek name Topazios, which
is that of an island in the Red Sea. The gem known to the ancients
as topaz, however, was probably not our topaz, but chrysolite. Topaz
usually occurs in gneiss, or granite, with tourmaline, mica, beryl, etc.
In Brazil it occurs in a talcose rock, or in mica slate. It is sometimes
in sufficient abundance to form an essential rock constituent. When
so occurring, however, it has not the transparent gem quality, but is
white and opaque. Much of the Brazilian topaz occurs as rolled
pebbles, one of which is shown in the accompanying plate. These
occur in the beds of streams, having been left behind, owing to their
superior hardness, after the rock in which they were formed has been
washed away. When colorless they are known in the region as
pingos d'agua (drops of water). The Portuguese call them " slaves' dia-
monds." A stone in the crown of Portugal, reputed to be a diamond
of 1,680 carats weight, and called the Braganza, is probably a topaz
of exceptional clearness and beauty.
The Brazilian topazes come mostly from the province of Minas G-eraes.
While those of greenish and bluish shades are found mostly in the form
of rolled pebbles, the yellow Brazilian topaz is found in the mother
rock. This is a decomposed itacolumite, of a white or yellow color.
The principal locality is near Ouro Preto.
! />The Russian topazes like that shown in the colored plate, come
from the Imperial mines in the Urals. Alabashka, near Mursinka,
is one of the most productive localities. The crystals occur in cavi-
ties, in granite, and are accompanied by crystallized smoky quartz,
feldspar, and mica. Superb gems are cut from these topazes, a fine
series of which is possessed in this country by the Field Columbian
Museum and the United States National Museum. The Russian mines
are owned and operated by the Russian Government, and the finest
specimens are reserved for the Imperial Cabinet.' ^In the southern
Urals, in the gold washings of the River Sanarka. yellow topazes are
found closely resembling those of Brazil. Associated with them are
a . j
amethysts, rubies, chrysoberyls, and many other precious stones. /^Topaz
crystals of good size and color are found quite abundantly in Japan,
although they have not yet been cut for gems to any extent. There
are many localities in the United States where topaz occurs, and it
is often of gem quality. The group shown in the plate illustrates
the occurrence of topaz at Thomas Mountain, Utah, a locality forty
miles north of Sevier Lake. These crystals are found in cavities in
the rock. They are never very large, but are usually clear and bright.
They occur in somewhat similar fashion at Nathrop, Colorado. In the
Eastern States topaz was first found at Trumbull, Connecticut. It
is here quite opaque, and not suitable for gem purposes. Good gem
topaz has been found at Huntington and Middletown, Connecticut,
however, and at North Chatham, New Hampshire. In these locali-
ties it occurs in pegmatitic granite.
Of other stones which are sold under the name of topaz, the most
common is the so-called Spanish or Saxon topaz. This is simply smoky
quartz, heated until it turns a yellow color. It can easily be distin-
guished from true topaz by the properties of the latter above given.
At the present time it is also quite a common practice to vend
ordinary colorless quartz under the name of topaz. These practices
are harmful to the reputation of true topaz, as these forms of quartz
lack several of the desirable qualities of that stone. The so-called
Oriental topaz is a yellow form of corundum. It is heavier and harder
than true topaz, and more valuable. fL About forty years ago topaz was
quite popular as a gem, and commanded three or four times its present
price. At the present time a stone weighing several carats may be
bought for two or three dollars. )
Topaz is often referred to by ancient writers, and is mentioned in
the Bible as one of the stones to be put in the ephod of the high
priest, as one of the gems worn by the king of Tyre, and as forming
one of the gates of the Holy City. The gem referred to in these
instances is, however, the modern chrysolite, while where chrysolite
is spoken of our topaz is usually meant.
A topaz presented by Lady Hildegarde, wife of Theoderic, Count
of Holland, to a monastery in her native town, emitted at night,
according to legend, a light so brilliant that in the chapel where it
was kept prayers could be read at night without the aid of a light;
a statement which might well be true if the monks knew the pray-
ers by heart.
The spiritual qualities associated with topaz are fruitfulness and
faithfulness. It is also said to confer cheerfulness upon its wearer.
The ancients believed that it calmed the passions and prevented bad
dreams ; that it discovered poison by becoming obscured when in con-
tact with it; that it quenched the heat of boiling water, and that its
powers increased and decreased with the increase and decrease of the
moon. Also that a topaz held in the hand of a woman at child-
birth would lessen her suffering, and that powdered and taken in wine
it would cure asthma and insomnia.
The character of this mineral in its employment as a gem is indicated
by the derivation of its name, which is from the Greek word kuanos,
meaning blue. While cyanite at times presents other colors, such as
gray, green, black, and white, only the transparent blue variety is used
for gem purposes. This is often dark blue, resembling sapphire in
color, and cut stones may thus considerably resemble the latter. Like
sapphire, cyanite is largely composed of aluminum, but it is a silicate
of this metal instead of an oxide. The percentage composition of
typical cyanite is alumina 63.2, silica 36.8. Cyanite is not as hard as
sapphire, being 5-7 in hardness. One of its peculiarities is that the
hardness differs in two directions. If one of the broad blades of the
mineral be scratched in one direction a hardness of 5 is observed, while
in a direction at right angles to this the hardness will be found to be 7.
The name of disthene, by which cyanite is sometimes known, refers to
the above differences, it being derived from dis, twice, or of two kinds,
and sthenos, strong. Cyanite usually shows slight differences of color in
different directions. It has a marked cleavage, which somewhat inter-
feres with its use as a gem, cracks being easily started in this direction.
Its specific gravity is comparatively high, being 3.55-3.65, nearly but not
quite equal to that of sapphire. Its crystals belong to the triclinic system.
Its occurrence is usually in mica schists and gneisses, it being often
accompanied by garnet and staurolite. The decay of the mother rocks
leaves it in form of rolled pebbles, in which manner it occurs in Russia,
India, and Brazil. Cyanite from all these localities affords good stones
for cutting, Monte Campione, in the St. Gothard region of Switzerland,
furnishes some of the finest crystals known. Nearly all that has been
used for gem purposes in this country has been obtained near Bakers-
ville, North Carolina. The comparative softness of cyanite is a bar to
its extensive use as a gem, although in respect to color and luster it is of
a pleasing character.
This mineral has the same chemical composition as cyanite, it being
a simple aluminum silicate. It differs, however, from that mineral in
color, specific gravity, system of crystallization and various other proper-
ties, so that there is little danger of mistaking the two.
Andalusite occurs generally as an opaque mineral, commonly in argil-
laceous and mica schists. The transparent pieces cut for gems are obtained
almost entirely from the province of Minas Geraes, Brazil, where they
occur in the beds of streams, together with topaz. These transparent
pebbles have a pale green color in one direction and in another are
brownish red. This difference of color is due to the pleochroism of the
mineral, which is strong, and the directions of which should be borne in
mind in cutting. It is when looked at in the direction of the vertical
axis that the reddish color of andalusite is apparent, while at right
angles to this the green color appears.
Andalusite crystallizes in the orthorhombic system, the crystals
usually taking the form of nearly square prisms. It has a marked
prismatic cleavage, which does not, however, interfere with the cutting of
it to any extent. Its luster is vitreous. In hardness it is somewhat
superior to quartz, the degree of hardness being 7.5. The specific gravity
is 3.16-3.20. Like cyanite, andalusite is infusible before the blowpipe,
and is not attacked by acids.
In addition to the use of the transparent forms of andalusite, men-
tion should be made of the fact that sections of the opaque crystals are
sometimes worn, being
prized on account of the
which they contain.
These result from the
Sections of andalusite crystal showing cross-like markings shape taken by inclu-
sions of carbonaceous
matter hi the crystal, which usually extend from end to end of
the same. Peasants of Brittany prize these especially as charms,
believing them of miraculous origin. This variety of andalusite is -tech-
nically known as chiastolite, from the Greek chiastos, meaning arranged
diagonally, and also as made, in allusion to the use of the "mascle" in
heraldry, which signifies a rhomb with open center. The name andalu-
site is from the province of Andalusia in Spain, whence the mineral was
first described. Chiastolites are found at various points in New England
and in California in this country, but sale for them is to be found chiefly
abroad. Kunz describes andalusite of a pink color, capable of affording
transparent gems, which is obtainable at Westford, Massachusetts, and
This mineral when sufficiently transparent to make a gem, furnishes
a dark, brownish red stone, not unlike some varieties of garnet in color.
It is similar also to garnet in hardness, 7-7.5, and specific gravity,
this being about 3.7. It differs, however, in crystallizing in the
orthorhombic system, and hence it is doubly refracting. The crystals
usually have the shape of six-sided prisms, often grouped in the shape of a
cross, the latter habit giving the mineral its name, from the Greek, stauros,
a cross. Groups of this shape are found
abundantly in Fannin County, Georgia, and
are there known as fairy stones, under the
belief that fairies make them. The peasants
of Brittany wear similar crystals as charms,
believing them of miraculous origin. The
Penitentes of New Mexico are said also to
have great reverence for the stone, each member of the sect being
accustomed to wear one around his neck. A traveler endeavoring
to buy one found it impossible to do so, the owner saying that he would
sooner part with one of his children. The stone had been blessed by
the priest, and its possessor believed that it insured him a long and
happy life, and protected him from all ailments and accidents.
In composition staurolite is a hydrous silicate of iron, magnesium,
and aluminum. It is generally infusible, and but slightly attacked by
acids. Rolled pebbles of staurolite occur in the gem gravels of Brazil,
and crystals suitable for cutting into transparent stones come from Swit-
zerland and Moravia. Staurolite is a common mineral in mica schists,
and in such a matrix occurs in several localities in this country, but no
transparent crystals have been found here.
Almandine Garnet (Alaska).
Essonite Garnet, cut.
Dem an told Garnet, cut.
Demantoid Garnet (Ural Mts.).
Alniandite Garnet, cut.
"Cape Ruby," cut.
Essonite Garnet and Diopside (Italy).
Epidote (Knappenwand, Austria).
Pyrope Garnet (Bohemia).
This mineral exhibits many varieties of color and of composition.
The color probably most often thought of in connection with it is dark
red, but it would be a mistake to suppose this the only color which it
may manifest. Green, red, rose, and brown are other colors which garnet
transparent enough to be used as gems exhibits, while among opaque
garnets may be found black and many varieties of the shades above
These variations of color are more or less connected with differences
of composition which it may be well first of all to consider. Garnet as
a mineral is a silicate. United with silica the element most commonly
occurring is aluminum. If calcium be united with these two, the variety
of garnet known as grossularite, or essonite, or cinnamon stone, is pro-
duced. If magnesium takes the place of calcium, then pyrope is formed.
If iron, we have almandite, and if manganese, spessartite. Another
variety of garnet, andradite, is composed of calcium and iron in com-
bination with silica, and still another, uvarovite, of calcium, chromium,
and silica. Though they seem to differ so much in composition, all kinds
of garnet crystallize in the same system, and are closely allied in all
their properties, so that it is an easy matter to distinguish garnet
of any variety from other minerals.
Forms of garnet crystals
Garnet crystals may be of the twelve-sided form known as dodeca-
hedrons, the faces of which have the shape of rhombs ; or the twenty-four-
sided form, known as trapezohedrons, the faces of which have the shape
of trapeziums. Quite as commonly occur crystals which are combina-
tions of these two forms, and then exhibit thirty-six faces, as in the crystal
from Alaska shown in the accompanying colored plate. Sometimes the
crystals attain considerable size. Perfect ones from Colorado weighing
fifteen pounds are known, and some two feet in diameter are reported
from North Carolina. A curious feature of garnet crystals is that of often
inclosing other minerals. The garnets from New Mexico, for instance,
when broken open are sometimes found to contain a small grain of
quartz. In the crystals from East Woodstock, Maine, only the outside
shell is garnet, and the interior is calcite. Other crystals are made up
of layers of garnet and some other mineral.
Garnet has a strong tendency to crystallize, and hence is usually
found as crystals. The grains of garnet found in the sands of river beds
and on beaches, though not often showing crystal form, may be really
fragments of crystals. Garnet is one of the most common constituents
of such sands because of its hardness and power of resisting decay. These
properties enable it to endure after the other ingredients of the rocks of
which it formed a part have been worn away. It is quite heavy as com-
pared with the quartz, of which the sand is mostly composed, and hence
continually accumulates on a beach, while the quartz is in part blown
away. In such localities it will always be found near the water line,
because the waves, on account of its weight, can carry it but a slight
distance inland. Practically all garnet is three and one-half times as
heavy as water, and some four times as heavy. As a rule, it is
somewhat harder than quartz, its hardness being 1\ in the scale of which
quartz is 7. Some varieties are, however, somewhat softer. Most varie-
ties of garnet fuse quite readily before the blowpipe, and the globules
thus formed will be magnetic if the garnet contains much iron. The
green garnet, uvarovite, is almost infusible, however. Garnet is not
much affected by ordinary acids, although it may be somewhat decom-
posed by long heating.
The name garnet is said by some authorities to come from the Latin
word granatus, meaning like a grain, and to have arisen in allusion to
the resemblance of its crystals in color and size to the seeds of the
pomegranate. The German word for garnet, granat, is the same as the
Latin word. Others think the word derived from the Latin name of the
cochineal insect, in allusion to a similarity in color.
The use of garnet for gem purposes seems to date back to the earliest
times. Among the ornaments adorning the oldest Egyptian mummies
there are frequently found necklaces containing garnet. The Romans
prized the stone highly, and it is a gem much used at the present
day, its hardness and durability and richness and permanency of color
giving it qualities desirable for a precious stone.
Two varieties of garnet, almandite and pyrope, may exhibit the dark
blood-red color especially ascribed to garnet. Almandite or almandine
garnet derives its name from Alabanda, a city of Asia Minor, in the
ancient district of Caria, whence garnet was first brought to the Romans.
* The finest almandite for a long time came from near the city of Sirian,
in the old province of Pegu, Lower Burmah. While this was the center
of supply, it is not known just where the garnets were obtained. Such
garnets are still known as "Sirian" garnets. Their color tends toward
the violet of the ruby, and gives them a high value, j^liere are several
localities in northern India where almandite is mined on a large scale,
and the stone is much used in Indian jewelry. Some of these localities
are Condapilly, Sarwar, and Cacoria/ Almandite is also found in Brazil,
in Australia, in several localities in the Alps, and in the United States.
Stones from all these regions are found suitable for cutting, the only
qualifications needed being sufficient size and transparency and good
color. The almandite of Alaska shown in the accompanying plate occurs
in great quantities near the mouth of the Stickeen River, but has not
been extensively cut on account of its being too opaque. Almandite
usually occurs in metamorphic rocks, such as gneisses or mica schists;
also in granite. It is also found in many gem gravels. From the ruby
it can be distinguished, as can all varieties of garnet, by its lower hard-
ness and single refraction of light. In artificial light, too, it borrows
a yellow tint, rendering it less pleasing, while the color of ruby grows
more intense. When almandite tends toward a brownish-red color it
is known as vermeille.
Pyrope, the magnesian variety of garnet, does not differ much in
color from almandite. Both are dark red, but while almandite tends
toward a violet tone, pyrope shades toward yellow. Pyrope is lighter
than almandite, the specific gravity being 3.7 to 3.8, while that of
almandite is 4.1 to 4.3. It is also less easily fusible. It rarely occurs
in crystals, and where found in place is always associated with the mag-
nesium-bearing rocks, peridotite or serpentine. It is thus probably always
of eruptive origin. Pyrope is a characteristic constituent of the diamond-
bearing rock of South Africa, and is the stone known in trade as u Cape
ruby." These garnets afford excellent gems.l^The home of the pyrope,
however, is, and has been for many centuries, Bohemia. Here it is found
in many localities, but chiefly in the northwestern part, near Teplitz and
Bilin. The garnets are found in a gravel or conglomerate of Creta-
ceous age, resulting from the decomposition of a serpentine. Sometimes,
however, they are found in the matrix, and are then often associated
with a brown opal. They are found by digging and separated by wash-
Mfag. Though of good quality the stones are small, those as large as a
hazelnut being found but rarely. Although the Bohemian garnets have
been known for many centuries, the industry of mining and cutting them
on a large scale is said not to have assumed any special proportions until
the advent of foreigners to Karlsbad. They spread a knowledge of the
stones to other countries, and a demand sprang up which has led
to the establishment of a great industry, and made Bohemia the garnet
center of the world. There are over three thousand men employed at
the present time simply in cutting the stones, and if to these be added
the number of miners and gold and silver smiths occupied in the mining
and mounting of the garnets, it is estimated that a total of ten thousand
persons is engaged in the Bohemian garnet industry. The stones are
used not alone for jewelry and for ornamenting gold and silver plate, but
also extensively for watch jewels and for polishing, f Excellent pyropes
are found in Arizona, New Mexico, and southern Colorado in our own
country. They occur in the beds of streams as rolled pebbles, and often
associated with the green chrysolite or peridot of the eruptive rock from
which they came. They are especially abundant about anthills, being
removed by the ants because their size stands in the way of the excava-
tions of the busy insects. The name pyrope comes from the Greek word
for fire, and is applied on account of the color of the stone.
Of quite similar origin is the name carbuncle, a term applied to
nearly all fiery red stones in Roman times, but now used to designate
garnets cut in the oval form known as cabochon. The word carbuncle
comes from the Latin word carbo, coal, and refers to the internal fire-like
color and reflection of garnets.
The calcium-aluminum variety of garnet, called grossularite, cinna-
mon stone, or essonite, is less used in jewelry than those above mentioned.
It is usually yellow to brown in color, but may be rose-red or pink. The
yellow grossularites resemble in color the hyacinth, and are sometimes
sold in place of the latter, but true hyacinth is much heavier and
doubly refracting.^ kAbout the only essonites or cinnamon stones avail-
able for gems come from Ceylon. These are of good size and color. \
Those from Italy, shown in the accompanying plate, are too small
to cut into gems, but surrounded as they are by light green chlorite
and pyroxene, make very pretty mineral specimens. Grossularite is
almost always found in crystalline limestone.
Green garnets are of two kinds, the calcium-iron garnet, known as
demantoid, and the calcium-chromium garnet, known as uvarovite. The
demantoid garnets come only from the Urals. They have a rich green
color, and make beautiful gems when clear and flawless. The name
demantoid refers to the diamond-like luster which they possess. The
stone is also known as " Uralian emerald." Uvarovite, named for Count
Uvarov of Russia, also makes valuable gems if found in pieces of suffi-
cient size and luster. It is found in Russia, in Pennsylvania, and in
That garnet has been known and used from the earliest times
has already been remarked. Under the name of carbuncle mention is
made of it in the literature of all ages, the feature noted being usually
the brilliant, fiery light which it gives iorth. According to the Talmud,
the only light which Noah had in the ark was afforded by a carbuncle,
and there are many Oriental tales regarding the size and brilliancy of
carbuncles owned by the potentates of the East. Occasionally carbuncles
were engraved, and some fine garnet intaglios are still known. The
greater abundance of the stone in modern times has led to its being less
highly prized than formerly, and to its being put to other uses than mere
adornment, but it perhaps contributes more largely to the comfort and
happiness of the world as it is now used than could ever have been the
case when it was the property only of kings. The virtues ascribed to
the garnet in earlier times were similar to those of the ruby, but in less
degree. It was emblematic of constancy, gave and preserved health, and
reconciled differences between friends. It kept off plague and thunder
if suspended from the neck, and increased riches and honors.
This mineral is known among the gems by many names. It is
often called chrysoberyl by jewelers, while the true chrysoberyl is called
chrysolite. It is also known by different names, according to its color,
it being called peridot when of a deep olive-green, olivine when of a yel-
lowish-green, and chrysolite when of a lighter or golden-yellow color.
The name chrysolite means gold stone. Again, some so-called emer-
alds are really chrysolite, a notable case being those shown in connec-
tion with the Three Magi in the Cathedral at Cologne. The so-called
"Oriental chrysolite" is yellowish-green sapphire; "Ceylonese chrys-
olite" is olive-green tourmaline ; " Saxon chrysolite " is greenish-yellow
topaz; " false chrysolite " is moldavite; " Cape chrysolite " is prehnite,
and so on. The various designations have evidently arisen by con-
founding different minerals similar in color, but it is an easy matter
in any case to distinguish the minerals by a test of their physical and
chemical properties. One feature distinguishing chrysolite from most
other gems is its relatively low hardness, which is 6f . It will thus
scratch feldspar, but is scratched by quartz and most other gems. Again,
it is relatively heavy, its specific gravity being between 3.3 and 3.4. Its
luster, too, while vitreous, has a slightly oily character, which can be
detected by a little experience. Chrysolite is easily dissolved by the
common acids, especially if powdered and warmed, the silica separating
in a gelatinous form, which is quite characteristic. In composition it is
a silicate of magnesium and iron, the relative percentages of the two
latter elements varying. In gem chrysolite the percentage of iron is
usually low, and a typical composition would be: silica, 41%, magnesia,
49.2 % , and iron protoxide, 9.8 % . Before the blowpipe chrysolite whitens,
but is generally infusible. It crystallizes in the orthorhombic system,
and is hence doubly refracting. The crystals have good cleavage in
one direction and partial cleavage in another. The fracture is con-
choidal. Chrysolite is a common constituent of eruptive rocks, but in
grains too small and too opaque to be used for gems.
Whence the large, transparent pieces of chrysolite used for gems
are obtained does not seem to be known. They are reported to come
from the Levant, from Burmah, from Ceylon, from Egypt, and from
Brazil; but the exact locality in none of these countries has yet been
ascertained by writers. Kunz states that all the chrysolite sold in
modern times is taken out of old jewelry, often two centuries old, so
that it is likely that the old localities are either forgotten or ex-
hausted. Recently, however, quite an amount of good chrysolite has
. come from a locality in Upper Egypt, near the Red Sea, and this is
doubtless one of the old sources of supply. The chrysolites at present
available are not of very large size, rarely exceeding an inch in diam-
eter. They are, however, of fine color and transparency, and make
a desirable gem when not exposed to hard usage. For ring stones
they scratch and wear away too easily. Excellent small chrysolites
come from Arizona and New Mexico, being found in sand in connec-
tion with the pyrope garnets previously mentioned. The chrysolite
is locally called "Job's tears," on account of its pitted appearance.
Chrysolite is an essential constituent of meteorites, and the grains
sometimes occur in these bodies of sufficient size and transparency
to be cut into gems of about a carat each. Such stones have a peculiar
interest on account of their origin.
Chrysolite is frequently mentioned in the Bible and in ancient litera-
ture; but it is pretty certain that much of the chrysolite so named
was our topaz. If this is true, the chrysolite of the ancients was
found on the island of Topazios, in the Red Sea. Diodones Siculus
says of the stone there that it was not discernible by day, but was
bright at night, so that it could be seen by patrols. They would
cover the luminous spot with a vase, and the next day come and cut
out the rock at the place indicated, when, upon polishing, the gem
would appear. The name chrysolite was also applied in former times
to a number of other yellow gems, such as zircon and beryl, stones
of a similar color being then usually classed together. Powdered chryso-
lite was used as a remedy for asthma, and held under the tongue was
believed to lessen thirst in fever.
This is a mineral possessing several interesting characters, and hav-
ing many qualities desired in gems, yet its use in jewelry is very
limited. It is comparatively common as one of the constituent min-
erals of metamorphic rocks, but in its ordinary occurrences it is not
suitable for gem purposes. It is only when occurring in large, trans-
parent crystals that pieces suitable for cutting can be obtained. Its
peculiar green color is one of its most striking characters, enabling it
nearly always to be recognized. This color is a yellowish green, known
as pistachio - green, and is hardly possessed by another mineral. It
frequently, however, shades to black on the one hand and brown on
the other, so that it cannot be taken alone as a criterion for determi-
nation. Epidote is quite strongly pleochroic ; that is, it exhibits differ-
ent colors in different directions, being often green in one direction,
brown in another, and yellow in another. It is usually cut so as
to show the green color, and the stone must generally be made quite
thin to get the proper transparency. Epidote is a rather hard and
heavy mineral, its hardness being nearly equal to that of quartz, and
its specific gravity 3.2 to 3.5. It is brittle, and has a basal cleavage.
Its luster is vitreous to resinous.
In composition it is a hydrous silicate of calcium, aluminum, and
iron, the darkness of its color increasing with a larger proportion
of iron. It is fusible before the blowpipe, but unattacked by acids
before fusing, flfthe finest crystals of epidote for cutting come from
the Knappenwand, in the valley of the Pinzgau, Austrian Tyrol.
Specimens of these are shown in the accompanying colored plate.
This occurrence was discovered in 1866. | Quite recently an occurrence
of epidote, more beautifully crystallized even than that of the Knap-
penwand, was discovered on Prince of Wales Island, Alaska ; but unfor-
tunately these specimens are too opaque for cutting. Being a rather
heavy mineral, epidote lingers among the pebbles of stream beds, and
material suitable for cutting is hence sometimes found in this way.
Brazil and North Carolina are localities where epidote of this sort
has been found.
This mineral affords transparent stones of pale brown, green, or yel-
low colors, which closely resemble in appearance cut gems of smoky
quartz, tourmaline, chrysolite, hyacinth, or essonite. They have a rich
luster due to a combination of resinous and vitreous characters, and
are sufficiently dichroic to be of interest from that point of view.
Nearly all the cut stones come from the occurrence at Mount Vesuvius
(whence the mineral obtains its name), or from one on the Mussa Alp,
in the Ala valley of the Piedmont plateau, Italy. The crystals from
Vesuvius are generally brownish to colorless, while those of the Pied-
mont are green.
The hardness of vesuvianite is 6.5, sufficient to give it a fair wear-
ing quality. Its specific gravity is 3.35 to 3.45. In composition it
is a complex silicate, chiefly of aluminum and calcium. It is fusible
before the blowpipe. It has a strong tendency to crystallize, the crystals
belonging to the tetragonal system, and usually appearing essentially
as short, stout prisms.
It is not an uncommon mineral, but is usually too opaque to make
desirable gems. Its occurrence is especially associated with limestone,
either as the result of metamorphism or direct volcanic eruption, as at
Vesuvius. A yellowish brown variety, known as xanthite, occurs at
Amity, New York, and an occurrence on the Vilui River, near Lake
Baikal, Siberia, is known as viluite.
The cut stones are made exclusively from clear crystals, which rarely
afford stones exceeding a few carats in size. The step or table cut is
the form usually given the stones.
Of the different names by which this mineral is known, cordierite
is in honor of the French geologist Cordier while the two others
indicate important characters of the mineral first, that it is of a violet
color (Greek, ion, violet, and lithos, stone); and second, that it has
two colors (Greek, dichroos, two-colored).
When cut as a gem the stone is usually known as water sapphire,
or saphir deau. In color it resembles the sapphire closely, although
the shade of blue which it exhibits is that known as Berlin -blue,
instead of the cornflower-blue of the sapphire. The sapphire, however,
exhibits nearly the same color throughout, while a cut stone of iolite,
if blue in one direction, will be seen on turning to be gray in another.
On this account, and by reason of its inferior hardness, it is not prized
as highly as the sapphire, and it has but a limited use. The hardness of
iolite is somewhat higher than that of quartz, being from 7-7.5. Its
specific gravity is nearly similar to that of the latter mineral, being 2.6
to 2.66. In composition it is a hydrous silicate of alumina, magnesia, and
iron. It is barely fusible before the blowpipe, and is not attacked by
acids. Its luster is vitreous, and its color may be imitated in glass;
but the strong dichroism of the native mineral cannot be copied. It
crystallizes in the orthorhombic system ; but clear, transparent crystals
are rare, the strong tendency of the mineral to alter on exposure caus-
ing them to become clouded and opaque. Pieces available for cutting
occur generally as grains in granite, or gneiss, or as rolled pebbles in
the beds of streams. /The finest of the latter come from Ceylon, and
this is the source of most of the iolite used in jewelry/ It occurs
similarly in Brazil, associated with topaz in stream gravels. Good iolite
for cutting has been obtained from granite in Haddam and Guilford,
Connecticut, in this country. Besides blue, iolite may also present
colors of yellow, green, or brown. Only the blue is cut, however,
and the cutting is made so as to show this color at the surface. It
is usually given the table, or step cut, but sometimes the cabochon,
especially if, as is sometimes the case, a star-like effect, like that of
the star sapphire, can be obtained.
This mineral has luster, hardness, and power of resistance to solvents
sufficient to fit it for use as a gem, but ordinarily lacks transparency
and brilliancy of color. Rutile is oxide of titanium, containing more
or less iron. Its usual color is reddish-brown, passing into black with
a higher content of iron. The latter variety, known as nigrine, gives,
when cut, a stone closely resembling the black diamond in appearance.
The luster of rutile is adamantine, like that of the diamond ; but owing
to its being rather opaque, its luster usually borders on the metallic
also. It is rarely sufficiently transparent to make clear
stones of any considerable size. At times, however, pieces
are found which cut into gems almost like the ruby.
Rutile is the mineral which usually forms the hair-like
crystals penetrating quartz and other minerals, and these
often have a blood-red color. The hardness of rutile
is 6-6.5. Its specific gravity is high, often enabling one
to recognize it by simply taking it in the hand. It equals
4.2. Rutile is infusible before the blowpipe, and is unattacked by acids.
What are perhaps the finest rutile crystals known in the world
come from Graves Mountain, Georgia. Here long, splendent crystals
are obtained, which are objects of sufficient beauty to be worn uncut.
It is characteristic of rutile to form groups of crystals, each meeting
the other at an angle, so as to form a complete polygon. These objects
make natural ornaments also.
Rutile crystallizes in the tetragonal system. The cut stones are
usually given the form of brilliants.
Titanite is one of the few minerals which possess, like diamond, an
adamantine luster. This luster gives to gems cut from titanite a rich
effect, but they lack depth of color and hardness sufficient to make them
stones of the first rank.
Titanite occurs in numerous colors, brown, yellow, and green being
the most common and characteristic. Stones cut from these are usually
distinctly -pleochroic, showing red and yellow in different directions,
while in one direction they may be colorless. Only
the transparent pieces are cut for gems. They
resemble chrysoberyl, topaz, garnet, or chrysolite, in
appearance. Their hardness is 5 to 5^, somewhat
below that essential for a good wearing gem. The
S hene specific gravity of titanite is 3.4 to 3.55. In compo-
sition it is a titano-silicate of calcium, the percent-
ages being, silica 30.6, titanium dioxide 40.8, lime 28.6. It is
fusible before the blowpipe to a colored glass. It is attacked by sul-
phuric and hydrofluoric acid. It crystallizes in the monoclinic system,
the crystals often having the shape of a wedge, whence the name sphene,
from the Greek sphen, a wedge, by which the mineral is often known.
The finest transparent crystals of titanite come from Switzerland,
being generally of a yellowish-green color. Kunz mentions crystals of
titanite from Bridgewater, Bucks County, Pennsylvania, over an inch in
length, which afford fine greenish-yellow or golden stones, weighing 10
to 20 carats.
This is a mineral occasionally cut for gem purposes, but not exten-
sively in vogue. It furnishes a stone of a clove-brown color, transparent,
and with glossy luster. It is somewhat deficient in hardness, being softer
than quartz, though harder than feldspar. Hardness 6.5-7. Before the
blowpipe axinite fuses readily, giving a pale green flame. It is not
attacked by acids. In composition it is a boro-silicate
of aluminum and calcium, with varying amounts of iron
and manganese. Besides occurring of brown color, it
may also be of blue, gray, or yellow shades, although
brown is the most common. Like epidote, iolite, tour-
maline, etc., axinite is strongly pleochroic, showing olive-
green, cinnamon-brown, and violet-blue in different direc- Axinite
tions, especially if examined with the dichroscope. It
crystallizes in the triclinic system, usually in thin, broad blades, which so
much resemble an ax that they have given the name of axinite to the
^/The best known occurrence of axinite, and that which yields the
finest crystals, is near Bourg d'Oisans, Dauphine, France. It occurs here
with albite, prehnite, and quartz. / There are several other occurrences
of the mineral in Europe and the United States, but few yield material
of sufficient size and transparency for cutting.
The species above named form a group of black, heavy minerals,
with pitchy or sub-metallic luster, which are occasionally cut when a-
brilliant black gem is desired. They are peculiar in their composition
in that they are salts of the rare earths, yttrium, cerium, tungsten
niobium, etc. They are therefore often known as rare earth minerals.
They have a hardness of 5-6, and a specific gravity of 5-6. The latter
is sufficient to distinguish them from any other of the black minerals
used in jewelry, such as jet and obsidian, the difference being at once
noticeable on taking one of either in the hand. Their color being a rich
velvet black, and their luster brilliant, they are superior in appearance
to the more extensively used black minerals, and should have a wider
vogue. Samarskite is perhaps the richest in color and luster of any of
the series, this being a deep velvety black. The minerals are found in
this country chiefly in North Carolina, although allanite is obtained also
in Virginia and Texas. In Europe they are found in Norway and the
Rutilated Quartz, polished (Brazil).
Rose Quartz, polished (Black Hills).
Smoky Quartz (Switzerland).
IOS, ir . w. MUKFtmO, CH
This is the most abundant of common minerals, and one which appears
in a great variety of colors and structures looking very unlike. In color,
hardness, transparency, and luster many of these varieties of quartz are
well suited for use as gems, but owing to their common occurrence they
are less highly valued than other minerals possessing perhaps no more
desirable qualities. Nevertheless the varieties of quartz have an extensive
use in jewelry, and deserve description in detail. The chemical composi-
tion of all varieties of quartz is the same, viz., oxide of silicon. The
physical characters are likewise nearly constant, and are as follows : hard-
ness, 7; specific gravity, 2.65; cleavage, none; fracture, conchoidal;
infusible before the blowpipe; insoluble in common acids.
The varieties of quartz fall naturally into two groups, the pheno-
crystalline (plainly crystalline), and cryptocrystalline (obscurely crystal-
line). Of these the phenocrystalline varieties will be considered first.
These include rock crystal, amethyst, smoky quartz, rose quartz, and
sagenitic quartz, with others of minor importance. The differences
between these varieties are almost wholly differences of color.
Rock Crystal. This is quartz in its purest form. Typically it is trans-
parent and colorless, but clouded and opaque occurrences are included
under this head. By the ancients it was supposed to be petrified ice, and
hence the Greeks applied it to their word for ice, from which we get our
word crystal. One reason for this belief was the fact that much of the
quartz known to them came from the high peaks of the Alps. They con-
cluded therefore that it was ice frozen so hard it could not melt. This
belief must have survived nearly to modern times, for in 1676 Robert
Boyle, the eminent physicist, thought it necessary to bring forward several
arguments to prove the falsity of the idea. One of these arguments was
that quartz was two and a half times as heavy as water, and another
that it was found in tropical countries.
Quartz in the form of rock crystal is now known to occur in all parts
of the globe, although the occurrences of clear, transparent rock crystal
suitable for cutting are comparatively few in number. Rock crystal is
frequently, though not always, found in the form of terminated crystals,
having usually the shape of six-sided prisms capped at one or both ends
by pyramids. For use in jewelry or for purposes of ornament rock
crystal is cut, the form of cutting depending on the size of pieces that
can be obtained clear. L The favorite use for the largest pieces is to cut
them into spheres or balls. This was done even in the times of the
Romans, the aristocratic ladies of that day carrying the spheres in
summer for the sake of the coolness they afforded. The same custom
prevails among the Japanese at the present time, and the industry of
making the balls is extensively carried on in Japan. Balls from four to
six inches in diameter have a high value, both on account of the rarity of
finding so large, transparent and flawless pieces of quartz and because
of the labor of making them// The smaller balls are somewhat in fashion
Forms of quartz crystals
in Europe and America at the present time as fortune tellers, the images
of objects seen through the spheres being supposed, according to a fancy
which has survived from an early period, to indicate the observer's future.
A superb example of carving in rock crystal is to be seen in the
Morgan collection of gems in the American Museum of Natural History
of New York City. This object is a globe four inches in diameter, on
which are outlined the continents and oceans, while a figure of Atlas
beneath supports the sphere.
Rock crystal is also cut into seals, paper-weights, and other orna-
mental objects, and the small pieces are used in enormous quantities for
cutting into stones for rings, pins, brooches, etc. These are often known
as " rhinestones," but also as "Lake George diamonds," "Brazilian
diamonds," and "diamonds" from whatever locality they come. These
make desirable stones as far as durablity is concerned, and are fairly
brilliant, but are not to be compared with the diamond in high
refractive powers. An attempt to pass off a rhinestone for a dia-
mond can be easily detected by the relative softness of the former, it
being possible to scratch it not only with diamond but also with corun-
dum or topaz. Rhinestones have little intrinsic value owing to the
common occurrence of the raw material. They do not therefore legiti-
mately bring a price much beyond that of the labor of cutting, which is
at present from a dollar and a half to two dollars a dozen for stones of
the ordinary sizes. Considerable rock crystal is used for making the
so-called "pebble" eye-glasses and spectacles. It is a common notion
that these are more beneficial to the eyes than glass. There seems to be
no good reason for this opinion, however, and unless the crystal is cut in
a certain definite crystallographic direction, that is, at right angles to the
prism, the light coming through to the eye of the wearer will be broken
up by double refraction, and may be positively harmful in its effects.
Another occasional use to which rock crystal is put is for making
mirrors, for which purpose it is said to be superior to glass in that it
does not detract from the rosiness of the complexion.
The chief source of the rock crystal used in the arts at the present
time is Brazil. In several provinces of that country, but especially those
of Minas Geraes and Goyaz, large, clear masses, often in the form of
crystals, are found loose in the soil. These are picked up and shipped to
various markets, furnishing a supply of excellent material at small cost.
In India considerable rock crystal is obtained from localities in the
government of Madras, and fashioned by the natives into various
The French and Swiss Alps, which probably furnished the raw mate-
rial to the Romans, still afford a small supply, of which limited use is
made. Quartz pebbles, derived doubtless from these Alpine sources, are
found in the bed of the Rhine and its tributaries, and it was to these when
cut that the name of rhinestones was originally applied.
The Island of Madagascar has since the middle of the seventeenth
century been noted for the large masses of clear quartz to be obtained
there. The quartz is found mostly in stream beds in the form of rolled
masses, but also occurs in crystals. Single pieces are found weighing
several hundred pounds. The Madagascar quartz furnishes the material
for most of the crystal balls sold as Japanese, many of these being not
even cut in Japan. In our own country several localities afford clear
quartz crystals, the best known being Hot Springs, Arkansas, and Little
Falls, New York. Those from the latter locality are doubly terminated,
and are sold quite extensively in their natural shape for jewels, as they
are small and brilliant.
The ancients prized rock crystal much more highly than we do,
because it answered them many of the purposes for which we now
find glass cheaper and more suitable. Wine-glasses were made from
it, though at great cost, a thousand dollars being considered a small
price for one. Lenses of rock crystal were used to concentrate the
rays of the sun to procure heat for cauterizing wounds and to light
fires, especially sacrificial ones.
The following lines, adopted from an early Roman writer, refer
to the latter custom :
"Take in thy pious hand the Crystal bright,
Translucent image of the Eternal Light;
Pleased with its luster, every power divine
Shall grant thy vows presented at their shrine;
But how to prove the virtue of the stone,
A certain mode I will to thee make known:
To kindle without fire the sacred blaze,
This wondrous gem on splintered pine-wood place,
Forthwith, reflecting the bright orb of day,
Upon the wood it shoots a slender ray
Caught by the unctuous fuel this will raise
First smoke, then sparkles, then a mighty blaze:
Such we the fire of ancient Vesta name,
Loved by th' immortals all, a holy flame;
No other fire with such grateful fumes
The fatted victim on their hearths consumes;
Yet though of flame the cause, strange to be told,
The stone snatched from the blaze is icy cold."
Globes of rock crystal were found among the ruins at Nineveh,
showing that the mineral was prized by that people. The Venetians
carried the art of engraving on rock crystal to a high degree of per-
fection, the effect of the figures being greatly enhanced by the addi-
tion of foils of different colors. Rock crystal was also formerly stained
many different colors to imitate other gems. The staining was per-
formed by heating the stones to redness and immersing them in a dye
possessing the desired color. The sudden change of temperature causes
minute cracks over the surface, imperceptible to the naked eye, which
absorb the coloring matter, and give the effect of complete coloration.
The use of quartz balls for divination has already been referred
to. Rock crystal has also long been credited with curative powers,
especially of hemorrhage and dysentery. To cure the former it is
applied to the bleeding part, and to cure the latter the powder mixed
with wine is drunk. It has also been regarded a cure for headache and
faintness if held in the mouth. In parts of Virginia it is supposed to be
a cure for sties, the sty being rubbed with the crystal three times
a day for three days.
Many of the tribes of the North American Indians use pieces of rock
crystal in their ceremonies, and regard them as having special magical
The Hindoos regard rock crystal a specific for consumption, leprosy,
and poisoning. It is known among them as "unripe diamond," and
may be substituted in medicine for diamond.
Amethyst. This term is applied to the violet or purple varieties
of quartz. It is derived from two Greek words meaning " not to inebri-
ate," and indicates the belief of the ancients that wine dr^nk from
cups made of this mineral could never have any deleterious effect.
All degrees of color are to be found in amethyst, from that only
slightly tinted to that so dark as to be almost opaque. The color
may be irregularly distributed, being sometimes in spots and again
shading uniformly in the same crystal from light to dark. Of these
colors the dark reddish-purple is the most highly esteemed, the paler
stones being less sought after. A reason for this is to be found in the
fact that by artificial light, especially if this contains yellow rays, pale
stones lose their violet color and become a dull gray. The deeply
colored amethysts, however, especially such as have been found in
Maine, change to a wine color by artificial light, and thus their beauty
is enhanced. Besides being of a deep purple color, a good amethyst
should be perfectly transparent and uniform in hue throughout. The
nature of the coloring matter of amethyst is not known. For a long
time it was thought to be oxide of manganese; but as the color disap-
pears on heating it is now believed to be a form of organic matter.
It has been noticed in some places where amethyst is mined that the
most deeply colored stones are at the surface, and that their color
grows paler as the vein is followed downward. The cause of this
phenomenon is not known. By partial heating the color of amethyst
can be changed to yellow, and some of the so-called citrine is made
in this way.
Much opaque and coarse quartz has an amethystine color, but such
is obviously of no value for gem purposes. The chief supply of the
amethysts used for jewelry at the present time comes from Siberia
and Brazil. ^The Siberian mines are located in the Urals in the vicin-
ity of Mursinka and Alabashka. The amethyst occurs in cavities in
granite, accompanied by beryl and topaz. Much of it is near the sur-
face, and it is also found lying loose.' The Brazilian amethysts occur
partly in cavities in a black eruptive rock (melaphyre), and partly
as pebbles in the river gravels, accompanied by chrysoberyl, topaz, etc.
Amethyst of gem quality is also found in Ceylon in gem gravels.
In our own country amethyst occurs abundantly, but not often of the
best quality for cutting. Some of the finest amethyst known has come
from Oxford County, Maine, but only a few specimens have thus far
been obtained. Delaware and Chester counties, Pennsylvania, have
furnished good amethysts, as well as Haywood County, North Caro-
lina. One of the best known localities for amethyst in America is
Thunder Bay, on the north shore of Lake Superior. Crystallized ame-
thyst is found here in large quantities coating veins in the rock.
While many of the crystals are highly colored they are not uniform
in color and lack clearness, so that few good gems have been obtained
Amethyst was much more highly prized in former times than now,
probably on account of its greater scarcity then. A celebrated amethyst
necklace, owned by Queen Charlotte, of England, which was valued at
the time it was made at $10,000, would probably be worth hardly $500
now. In spite of the comparative abundance of amethyst at the present
time there is a constant demand for good stones, since no other gem
affords its charming violet color. One dollar a carat is an average
price for amethyst at the present day, and this value remains about
the same even with an increase in size of the stones, as large amethysts
are comparatively common. The step cut is usually adopted for ame-
thyst, and is well adapted to it. Brilliants are, however, common,
and the mixed cut also often gives a good effect. Amethyst was
often worn in the Middle Ages as an amulet and preserver of the
wearer in battle. It was supposed to be serviceable to persons having
petitions to make to princes, and to be a preventive of hailstorms and
locusts. It has also long figured as a pious or episcopal gem, being the
stone which is regarded as imparting especial dignity or beauty to the
property of the church. It is a gem especially sacred to St. Valentine,
he being said always to have worn one.
Rose Quartz. This form of quartz, the color of which is indicated
by its name, is rarely of sufficient transparency to be prized as a gem.
Cut, however, into various ornaments, it makes objects of considerable
beauty. Its luster, instead of being glassy like that of other forms of
quartz, is nearly always more or less greasy. The ingredient which
gives it color is not known. * It is probably some organic matter, since
the color disappears on heating and, unfortunately for the extended use
of the stone, often fades considerably on exposure to light. Unlike
other varieties of pheno-crystalline quartz, rose quartz has never yet
been found in the form of distinct crystals. There are numerous locali-
ties whence rose quartz of good color may be obtained, although it is not
of so common occurrence as most other varieties of quartz. The best
rose quartz in this country comes from Oxford County, Maine, and the
Black Hills. Foreign localities are the Urals, Brazil, and Ceylon.
Smoky Quartz. This variety of quartz is often known as " smoky
topaz," a misleading term, since the mineral is not topaz. As its
name implies, its color is like that of smoked glass, all gradations occur-
ring between a mere tinge to color so dark as to render the mineral
practically opaque. The color often varies considerably in the same
crystal, being darker and lighter in spots. The coloring matter is
undoubtedly carbonaceous and organic in nature, for when a crystal is
heated it gives off a smell of burning organic matter, and by heating for
some length of time the coloring may be entirely burned out. At an
intermediate stage in such heating the color becomes brown or yellow,
and stones of this color are often cut as gems, and known by the name
of "Spanish topaz" or "citrine." True citrine is, however, transparent
quartz with a natural yellow color. The most remarkable crystals of
smoky quartz known are some that were found in 1868 in a hollow in
granite in a locality in the Canton Uri, Switzerland. About three thou-
sand pounds of well-formed crystals were there found, the largest and
best of which are preserved in the Berne Museum. The same region,
and neighboring ones in the Alps, have also furnished large quantities
of smaller crystals of notable perfection in form, and of fine quality.
The next most important locality for smoky quartz is in the vicinity
of Pike's Peak in the State of Colorado. Here the smoky quartz occurs
in pockets in a coarse pegmatite accompanying amazon stone and other
feldspars. Kunz mentions one crystal from this locality which measured
four feet in length. Large, flawless pieces have been found, which have
been cut into facetted stones weighing a pound or more. Alexander
County, North Carolina, has also furnished much excellent smoky quartz.
Large clear crystals and masses have been found at Auburn, Maine, one
of these crystals being nearly two feet in length. These have furnished
material for balls and other objects. Smoky quartz is sometimes known
by the name of cairngorm stone, from its occurrence at Cairngorum,
near Banff, in northern Scotland. The quartz from this locality was
at one time widely distributed, and came to be regarded as the national
gem of Scotland. The cairngorm stone occurs in connection with masses
of granite, and is obtained by digging shallow pits or trenches in areas
where considerable decomposition has taken place. The stone as used in
jewelry is usually heated to give it a yellow color. Little of it is mined
at the present time.
Smoky quartz has the physical and chemical properties of rock crys-
tal, by which it can be distinguished from other brown gems, such as
axinite or brown diamond. It is usually cut in the form of the brilliant
or the step cut. Being available in large, clear pieces, it is also used for
seals, brooches, penholders, etc. It exceeds rock crystal little if any
in market price.
Sagenitic Quartz. This form of quartz is variously known as " sage-
nite," "fleche d'amour" (love's arrow), "hair stone," "needle stone,"
and if the included mineral be rutile, " rutilated quartz." These terms
all refer to colorless crystallized quartz which is penetrated by hair-like
crystals of other minerals. An illustration of the occurrence is given
in the accompanying colored plate. Of the minerals so included rutile
is the most common, but tourmaline, hornblende, epidote, goethite, and
others occur. The inclusions have doubtless been formed in the quartz
by crystallizing at the same time with it, the quartz in this case being
the "host." The length of the included crystals may be considerable.
Some of the rutilated quartz from Madagascar has single included crys-
tals six inches long. The quantity of the included mineral may vary
from a few long, scattered individual crystals to a multitude of short
ones. For cut stones, pieces of the latter sort are usually preferred.
Some of the prettiest effects are produced when the included mineral is
rutile, and is sufficiently transparent to be of a blood-red color by trans-
mitted light. By cutting suitable pieces of this sort into the form of
hearts, the effect indicated by the term "love's arrow" can be prettily
obtained. Often the included crystals cross each other nearly at right
angles, thus giving the appearance of a network. It is on account
of this appearance that the name sagenite, from the Greek sagene, a net,
is given. Sagenitic quartz is obtained in various localities. Madagascar
is perhaps the chief source of supply at the present time, much excellent
material being obtained there. The rock crystal of Brazil is frequently
sagenitic also. Several localities in the United States furnish sagenitic
quartz, among them being North Carolina, Rhode Island, and California.
Perhaps the finest specimens ever seen were gotten from some boulders
found in the vicinity of Hanover, New Hampshire, in the years 1830-
1850. Crystals of quartz containing hair-like crystals, or massive o:-
scale-like inclusions of chlorite, are obtained in Japan, which are pre-
pared for ornamental purposes simply by smoothing and polishing the
natural crystal surfaces.
" Cat's-eye" " Tiger-eye." These are forms of quartz containing
fibrous inclusions, which, instead of being scattered, are massed together,
so that upon a polished surface a sheen like that of silk is seen by
reflected light. The term of Occidental cat's-eye is often applied to
cat's-eye of this sort, in distinction from the Oriental cat's-eye com-
posed of chrysoberyl. " Tiger-eye " is made up of somewhat coarser
fibers than cat's-eye. It is of a golden yellow color, while the color of
cat's-eye varies from pale blue and pale green to reddish-brown. A blue
variety occurring with the South African tiger-eye is known as " hawk's-
eye." A piece of either of these minerals if cut en cabochon in a proper
manner exhibits a band of light across it, changing in position when the
stone is turned. The included fibrous mineral which gives the effect is
asbestos. In the tiger-eye obtained from South Africa all gradations are
found between crocidolite, which is a fibrous form of amphibole, and
quartz, the tiger-eye being formed by a replacement of the crocidolite
by the quartz. Thus the structure of the crocidolite is retained, but
the stone has the hardness and luster of quartz.
Cat's-eye comes chiefly from Asia, the Malabar Coast of India and
the Island of Ceylon being the localities most prolific in it. In the latter
locality it accompanies the Oriental or chrysoberyl cat's-eye. It is, how-
ever, much less valuable than the latter.
^Nearly all the tiger-eye used at the present time comes from South
Africa. It is found in a range of quartzose schists called the Asbestos
Mountains, located in Griqualand, and extending from Griquatown in a
northeasterly direction toward the Transvaal. Griquatown is about one
hundred miles west of Kimberley. Other localities northward along
the Orange River also furnish tiger-eye. The mineral as found varies
in color from blue to yellow, according to the degree of oxidation of
the iron of the mineral. As already noted, the blue is called hawk's-
eye. Owing to the quantity of the raw material available tiger-eye brings
a low price, and has dropped out of fashion to a considerable extent.
Twenty-five years ago it commanded a price of $6 a carat, being rated as
high as turquois at the present day. Owing to the competition of two
dealers at that time and the appearance of an immense supply, the price
quickly fell to less than twenty-five cents per pound, and the demand
for it almost ceased. ^
The cutting of tiger-eye is now largely carried on in Oberstein and
vicinity at the great agate-cutting establishments. Ring and brooch
stones, dishes, and vases are some of the objects made from it.
Aventurine. Quartz known by this name contains inclusions, not
in the form of fibers, but in that of scales of some bright mineral, such
as mica or hematite. The quartz thus presents a spangled appearance.
The spangles, according to the size of the included scales, may be
coarse or fine. The choicest aventurine is that in which each scale
gives a distinct reflection. The quartz base may be brown, red, yellow,
or black, or rarely bluish or greenish in color, and the spangles usually
silvery or golden. The aventurine most commonly used is of a reddish
yellow color with a coppery sheen. Aventurine quartz resembles the
form of feldspar known as sunstone in appearance, but can easily
be distinguished from it by its greater hardness.
The best known localities for aventurine at the present time are
the Ural and Altai mountains in Russia. In the former it occurs in
the vicinity of Slatoust, in strata of mica schist, and in the latter not
far from Kolivan. The aventurine from the latter locality is cut into
large vases and dishes. One of the finest of these is to be seen in
the Museum of Practical Geology in London. This vase was pre-
sented by Nicholas I. to Sir Roderick Murchison in recognition of his
services in investigating the geology of the Russian empire. Aventurine
is said to be highly regarded in 4 "*China, the imperial seal being always
made from it. India and several localities in Europe furnish aventurine ;
but none of good quality has as yet been found in the United States.
Owing to the facility with which it can be obtained in masses it is not
used extensively except for making large ornamental objects. Together
with sunstone it can be quite successfully imitated in glass.
Crypto-crystalline quartz. The crypto-crystalline (obscurely crystal-
line) varieties of quartz are many. The following may be named as the
most important: Chalcedony, carnelian, sard, chrysoprase, prase, plasma,
bloodstone, agate, onyx, sardonyx, jasper, basanite, flint, and hornstone.
The distinctions between the different varieties are loose, and are differ-
ently stated by different authorities. Some class agate, onyx, sardonyx,
plasma, and carnelian as varieties of chalcedony, while others consider
chalcedony a simple variety.
The chalcedonic varieties of quartz agree in having a fibrous struc-
ture and in being somewhat softer (hardness 6^) and somewhat lighter
(specific gravity 2.6) than crystallized quartz. They also break with
more difficulty than quartz, being very tough. The varieties differ
among themselves chiefly in color.
Chalcedony has a waxy luster, and is usually translucent rather
than transparent. The transparent forms are known as "Oriental,"
the translucent as " Occidental " chalcedony. Common chalcedony has
little color, shades of gray and blue being the most common, although
other tints occur. It usually presents rounded surfaces which have
grape-like, kidney-like, or stalactitic forms. It occurs coating other
rocks or minerals, or lines cavities, or fills veins and clefts. It is never,
so far as known, deposited in any other way than by percolating
waters. At Tampa Bay, Florida, the waters containing chalcedony
have penetrated corals and preserved them, often giving forms show-
ing the shape of the coral outside and a cavity within. Throughout
the " Bad Lands " of the West, clefts in the hills are often filled with
sheets of chalcedony, varying in thickness from that of thin paper
to nearly an inch. These chalcedony veins ramify in all directions,
and often extend for many rods without interruption.
When the chalcedony is penetrated by branching forms of manganese
or iron oxide, the forms known as " mocha stones " and " moss-agates "
are produced. These are not due to vegetation, any more than the
similar forms of frost on our window-panes. Moss-agates are found
in numerous localities in the States of Utah, Wyoming, Colorado, and
Montana. Kunz remarks that " no stone that is used in jewelry in the
United States is cheaper, more beautiful, or more plentiful than the
moss-agate." The best occur as rolled pebbles in the beds of streams.
The name " mocha stone," sometimes applied to moss-agates, is either
due to the fact that those first used came from Mocha in Arabia,
or it is a corruption of the word moss-agate. The finest moss-agates
now known come from
India. A white variety of
minute blood-red spots,
is known as St. Stephen's
stone. Chalcedony was
formerly used much more
and more highly prized
than at the present time.
It was especially employed
for seals and rings, but
also for plates, cups, and
vases. These were often
engraved in the most
elaborate manner, the
hardness and toughness
. , , , . ,,
oi the stone being well
suited to this purpose. The sentiment of the stone is : " A disperser of
melancholy." The name chalcedony is from Chalcedon, a city in Asia
Minor, where the original chalcedony was found. This mineral was
probably not like our modern chalcedony, but a green quartz. This
chalcedony is mentioned in the Book of Revelations as one of the
foundation stones of the Holy City.
Carnelian is a red variety of chalcedony; sard a brown variety.
All gradations between these shades of course occur, those of the
reddish cast being the most common. The most highly prized color
for carnelian is a deep blood -red, appearing darker red in reflected
light. The lighter red and yellowish shades are less desirable, stones
of these shades being known as " female " carnelians, while those of the
darker shades are known as " male " carnelians. The colors are due
to oxides of iron, and can sometimes be changed by heating. Thus,
the yellowish and brownish carnelians, being colored by iron hydroxide,
can be changed by heating to red, the water being driven off and iron
oxide left. The heating may be done in the sun, or by some other
slow means. Even olive-green stones are changed in India to red by
this process. The color may also be introduced artificially, by allowing
the stones to lie in a mixture of metallic iron and nitric acid, or of iron
sulphate for a while. In this way the iron salt needed for the color-
ing matter can be absorbed by the stone, and this be changed after-
wards to oxide by heating. The best carnelians come from India,
but good stones are also obtained in Siberia, Brazil, and Queensland.
Carnelians are cut usually in oval and shield-like shapes. They were
much employed by the ancients for intaglios, who believed them to
have the power of preventing misfortune, curing tumors, preventing
hoarseness, and strengthening the voice. They also insured victory in
all contests save those of love. Used as a powder or worn in a ring
carnelian was believed to prevent bleeding at the nose, and the belief
survives to some extent to the present day.
The name carnelian is, according to some authorities, derived from
the Latin word caro, carnis, flesh, and refers to the color of the stone ;
according to others, it is from the Italian word carniola, which has the
Sard, of typical brown color, is much rarer than carnelian, and
possesses a higher value. The sardius mentioned in the Bible as form-
ing one of the stones of the high priest's breastplate, was undoubtedly
a carnelian. The name was derived from Sardius, a city of Lydia,
whence fine carnelians are obtained. Sard occurs with carnelian and
grades into it. The best sard should be of a deep brown color, shading
to orange but with a reddish tinge by transmitted light. The color
can be artificially produced by methods similar to those described
below for coloring agates, but long and careful treatment is required.
The sard was believed by the ancients to confer cheerfulness and cour-
age and to be a preventive of noxious humors.
Chrysoprase and prase are terms applied to an apple-green to bright
green chalcedony, or compact, jasper-like form of quartz. Some author-
ities, however, call the green chalcedony plasma, and restrict the term
chrysoprase to the green compact quartz. The terms cannot be accur-
ately distinguished. Most chrysoprase now in use comes from localities
in the province of Silesia, in Germany, where it occurs in thin layers
and veins in serpentine. The green color is due to nickel oxide,
which is present in the stone to the amount sometimes of one per cent.
The first discovery of the stone is said to have been made by a Prussian
officer in 1740. The stone was especially fancied by Frederick the Great,
so that he had two tables made of it, and used it frequently in mosaics.
The color fades with light and heat; but it is said can be restored
by burying the stone in moist earth for a time. Beautiful chrysoprase
comes from India, and there are a few localities in our own country
where it is found, it being usually associated with nickeliferous deposits.
The name chrysoprase comes from two Greek words, meaning golden
leek, and refers to the color of the stone. By the ancients it was
supposed to possess the virtues of the emerald though in less degree.
They thought that it lost its color in contact with poison, and was an
excellent cordial and stimulant.
Plasma, as already stated, is a name applied to green chalcedony,
or by some to green jasper. The name comes from the Greek for image,
and shows that the stone was largely used for seals and other engraved
work. Most of that known at the present time comes from India
Bloodstone is a variety of plasma containing spots of red jasper,
looking like drops of blood. Another name for bloodstone, by which
it was chiefly known by the ancients, is heliotrope. This name is
derived from two Greek words, meaning " sun turning," and refers
to the belief that the stone when immersed in water would change
the image of the sun to blood-red. The water was also said to boil and
overflow the containing basin. As late as the middle of the seventeenth
century bloodstone was used as a cure for dyspepsia, and when powdered
and mixed with honey was considered a remedy for tumors. If rubbed
with the juice of the heliotrope it was supposed to render its wearer
invisible. It was often used for stopping the flow of blood, either by
touching the bleeding spot with it, or by wetting the stone in water
and holding it in the hand. It was also often used for carvings
representing the head of Christ, one fine specimen of such work being
preserved in the Field Columbian Museum. The ancients had a tradition
that the stone originated at the crucifixion of Christ, from drops of blood
drawn by the spear thrust in his side, falling on a dark green jasper.
The stone takes a beautiful polish. To be of the best quality, it should
have a rich, dark green color, and the red spots should be small and
uniformly distributed^ The supply is obtained almost wholly from India,
especially from the/'Katniawar Peninsula west of Cambay, whence agate,
carnelian, and chalcedony are also obtained. Fine examples have also
come from Australia and a few from Brazil.
Agate differs from other forms of quartz in being made up of
minute layers, which are variegated in color. The colors may appear
in the form of bands or clouds. The banded agates appear to be
made up of parallel layers, sometimes straight, but more often wavy
or curved in outline. These layers or bands differ in color from
one another, exhibiting shades of white, gray, blue, yellow, red, brown,
or black. To the naked eye they appear to vary in width from the
finest lines to a width of a quarter of an inch or more. In reality, all
the bands visible to the naked eye are made up of finer ones, to be seen
only with the microscope. Thus in a single inch of thickness of agate
Sir David Brewster, using the microscope, counted seventeen thousand
and fifty layers. Besides differing in color, the layers differ in trans-
parency and porosity, and these properties add to the variegated appear-
ance of the agate.
On account of their beauties of color and outline, agates have been
known and prized from the earliest times. They are mentioned by many
of the ancient Greek writers, and the name agate is a corruption of the
name Achates, a river in Sicily, whence the first stones of this kind used
by the Greeks were obtained. This and neighboring localities continued
to be the source of supply until the fifteenth century, when agates were
found to occur in large quantities near Oberstein and Idar, on the banks
of the River Nahe, in the duchy of Oldenburg.
The industry of cutting and polishing agates on a large scale was
soon established there, and these places are to this day the center of the
agate industry. The agates used most extensively at the present time
are not, however, those found about Oberstein, but come from a region
about one hundred miles in length, extending from the Province of Rio
Grande do Sul in Southern Brazil into Northern Uruguay. The agates
in this region, first discovered in 1827, so surpass in size and beauty
those from any other known locality, that they form at the present time
almost the only source of supply. They are shipped in large quantities
as ballast to Oberstein and Idar, and here the work of cutting, polishing,
and coloring them is performed. The discovery that the attractiveness
of agates could be enhanced by artificial coloring was made about the
beginning of the nineteenth century. The natural colors are rarely of a
high order, being often only variations of white and gray, or dull yellows
and reds. Through the difference of porosity of the different layers,
however, and the consequent different absorption of coloring ingre-
dients, colors can be artificially introduced which produce lasting and
Banded Agate (Brazil).
Banded Agate (Lake Superior).
COPYRIGHT 1901, BY A. W. MUMFORD, CHICASO.
pleasing effects. Most agate used for ornamental purposes at the present
time is, therefore, artificially colored. The method of coloring is to boil
the stone in honey for a number of days, or even weeks, according
to the porosity of the agate and the color desired, then to immerse it
in hot sulphuric acid. The acid chars to a brown or black the carbon
of the honey which has been absorbed by the stone. Various coloring
ingredients, such as oxides of iron, salts of nickel, Prussian blue, etc.,
may be added to the liquids employed at some stage of the process,
and thus different colors be obtained.
Agates of considerable beauty, though not of great size, are found in
many places in the United States. Those of Agate Bay, Lake Superior,
have rich colors, and make attractive charms and- other ornaments.
Agates are found in the beds of many streams in Colorado, Montana,
and other regions of the Rocky Mountains. They occur all along the
Mississippi River, especially in Minnesota, also along the Fox River, Illi-
nois, in the trap rocks along the Connecticut River, and on the coast of
California. While many of these agates are of great beauty, their use
and sale is not likely to be anything more than local, since the Brazilian
agates can be supplied so cheaply from Germany.
The layered structure of agates is due to successive depositions
of silica by water flowing through cavities in rocks. Rising and falling
alternately through the rocks the water leaves a mark of each advance
or retreat in the form of an additional layer deposited upon the interior
walls of the cavity. Agates, therefore, grow from the outside inward.
The process may go on until the cavity is entirely filled or may cease
at any time. If the cavity is small and nearly circular, and becomes
entirely filled, the kind of agate known as "eye-agate" is produced.
If water remains in the cavity for some time crystals, such as are some-
times seen, will be formed. The nodule of silica or agate formed by
the percolating waters is harder and more resistant than the surround-
ing rock. Hence it remains after the surrounding rock has been worn
away. We can thus understand why agates should be found, as they
usually are, on sea or lake beaches, or in the beds of streams.
The different colors seen in the natural agates are produced by traces
of organic matter or of oxides of iron, manganese or titanium contained
in the waters which formed them.
Agates are not used as extensively as they once were for ornamental
purposes. In the years of 1848-50 agate jewelry was very fashionable,
and was extensively worn. At the present time, however, the principal
use of agate in jewelry is for breastpins and watch-charms. For orna-
mental purposes it is used in pen-holders, knife-handles, and vases. Its
use for large marbles was once quite common, but glass marbles of the
same size, and still called "agates," are now generally substituted. In
fine mechanical work, such as bearings for delicate instruments, and in
tools for polishing and grinding, agate is still extensively used.
Various curative properties were formerly attributed to the agate,
belief in some of which still survives, especially among Mohammedan
peoples. It was regarded as a cure for insanity, and as a preventive of
skin diseases. It symbolized health and wealth, and was supposed to
render its wearer gracious and eloquent.
Onyx and sardonyx are varieties of agate in which the layers are in
even planes of uniform thickness. This structure enables the stone to
be used for engraving cameos. As is well known, these are so made that
the base is of one color and the figure of another. This art of making
cameos reached a high degree of perfection among the Romans, and
many superb examples of it have come down to us. The word onyx
means a nail (finger-nail), and refers to some fancied resemblance, per-
haps in luster, to the human nail. Sardonyx is a particular variety
of onyx in which one of the layers has the brown color of sard. Other
kinds of onyx are those known as chalcedonyx and carnelionyx, in refer-
ence to the color of the intervening layers. So-called Mexican onyx is
composed of quite a different mineral from the onyx here considered, it
being made up of calcite rather than quartz. Hence Mexican onyx can be
scratched easily with a knife, while quartz onyx cannot. Mexican onyx
has, however, the banded structure of quartz onyx, and it is in allusion
to this undoubtedly that the name has been applied. A sardonyx upon
which Queen Elizabeth's portrait was cut constituted the stone of the
famous ring which she gave the Earl of Essex as a pledge of her friend-
ship. It will be remembered that when the earl was sentenced to death
he sent this ring to his cousin, Lady Scroop, to deliver to Elizabeth.
The messenger by mistake gave it to Lady Scroop's sister, the Countess
Nottingham, who being an enemy of the earl's did not deliver it to the
queen, and the earl was executed. On her deathbed the countess is said
to have confessed her crime to the queen, who was so infuriated that she
shook her, saying "God may forgive you, but I cannot."
In the Middle Ages sardonyx was used as an eyestone, and is employed
in Persia to this day for the cure of epilepsy. It was supposed by the
ancients to be an entirely different stone from the onyx. To it was ascribed
the property of conferring eloquence upon its wearer, and it especially sym-
bolized conjugal bliss-. It is mentioned in Revelations as one of the stones
forming the foundations of the Holy City. Onyx and sardonyx which
come from the Orient are esteemed of much higher value in trade at the
QUARTZ (obscurely crystalline).
Bloodstone, polished (India).
Tiger Eye, polished (South Africa).
Agate and Carrielian, polished (Lake Superior).
Kibbon Jasper, polished (Siberia).
present time than those prepared in Germany. There seems to be no
good reason for this, however, as the latter can be so skillfully made
that it is impossible to distinguish them from the Oriental stones.
Jasper includes in general nearly all varieties of impure, opaque,
colored, crypto-crystalline quartz. In color it may be red, yellow, green,
brown, bluish, and black. To many of the pebbles found on almost any
sea or lake shore, or in the beds of streams, the name jasper may prop-
erly be applied. If it occurs banded, that is, in stripes of different colors,
it is known as ribbon jasper. The different colors of jasper are due
to different impurities which it contains. These may be clay, iron
oxides, or organic matter, and at times reach a quantity as high as
twenty per cent. The color often varies irregularly in a single stone,
giving different effects, and sometimes imitating paintings. Jasper
which can be used in the arts is very widely distributed. Good red
jasper is obtained in Breisgau, and near Marburg in Germany. Much
brown jasper comes from Egypt. What is known as " Sioux Falls
jasper," from Sioux Falls, South Dakota, is chiefly of a brown color.
This stone was highly prized by the Indians for its color, and is the
"jasper" referred to by Longfellow in Hiawatha:
"At the doorway of his wigwam
Sat the ancient Arrow-maker
In the land of the Dacotahs,
Making arrow-heads of jasper,
Arrow-heads of chalcedony."
The yellow jasper used for mosaics comes chiefly from Sicily, but
as good could be obtained in many places in our own country. The
green jasper of the present time is obtained chiefly in the Urals, and
is to a considerable extent worked there into ornamental pieces. The
Chinese^ prize green jasper highly, the seal of the emperor being made
from it. Some jasper of a bluish shade is found in nature; but that
of a deep blue tinge is always artificially colored by Prussian blue.
It is then sometimes known as " false lapis "; that is, false lapis lazuli.
Kibbon jasper is found in Saxony, but chiefly comes from the Urals.
The qualities which make jasper of use in the arts are its color,
opacity, and capacity for taking a polish. At the present time it
is not much used except for mosaic work, and for small boxes, vases,
and dishes. The ancients, however, prized it highly and used it exten-
sively. It is one of the stones prescribed in the Book of Exodus to be
worn in the ephod of the high priest, and also forms one of the gates
of the Holy City, as described by St. John in Revelations. It is prob-
able that the jasper referred to in these instances was of a dark green
color, as this was the tint most prized in early times. Green jasper
was also called emerald in some instances. The banded varieties were
much used for cameos, specimens of which are still extant. By taking
advantage of the colors of the different layers, colored objects were
made, such as one which shows the head of a warrior in red, his helmet
green, and breastplate yellow.
Jasper worn as an amulet was regarded a preventive of sorrow, and
mottled jasper suitably engraved was believed to protect its wearer from
death by drowning. It was a charm against scorpions and spiders, and
strengthened the chest, lungs and stomach, according to beliefs held in
the Middle Ages.
Basanite, also known as Lydian stone, or touchstone, is chiefly used
for trying the purity of metals. Its value for this purpose depends on its
hardness, peculiar grain, and black color. Different alloys of gold give
different colors on the stone, and thus enable one to determine the fine-
ness of the gold. Also, if an object is plated, by giving it a few strokes
on the stone, the different color of the gold and base will be revealed.
Basanite is a black variety of crypto-crystalline quartz, differing from
jasper in being tougher and of finer grain, and from hornstone in not
Flint is likewise an opaque quartz of dull color. It differs from
jasper in breaking with a deeply conchoidal fracture and a sharp
cutting edge. It is also often slightly transparent, and has a some-
what glassy luster. These properties have led to its extensive use
by the Indians and by nearly all primitive peoples for the manufac-
ture of weapons and implements. Hornstone is more brittle than
flint, and has a splintery rather than a conchoidal fracture. A num-
ber of other subvarieties of crypto-crystalline quartz occur, but they
are not important as gems.
Precious Opal in matrix (Queensland).
Precious Opal (New South Wales).
Wood Opal (Idaho).
Precious Opal (New South Wales).
Prase Opal (Germany).
Precious Opal (New South Wales).
Fire Opal in matrix (Mexico).
"The opal, when pure and uncut in its native rock," says Ruskin
in his lecture on Color, " presents the most lovely colors that can be
seen in the world, except those of clouds."
While not all may share the great art critic's preference for uncut
stones, there are few probably who do not join heartily in admiration
of the brilliant gem from whose depths come welling up tints of so
varied hue that we appropriately speak of them as colors at play.
Regarding these colors Ruskin says further : " We have thus in nature,
chiefly obtained by crystalline conditions, a series of groups of entirely
delicious hues ; and it is one of the best signs that the bodily system
is in a healthy state when we can see these clearly in their most
delicate tints, and enjoy them fully and simply with the kind of
enjoyment that children have in eating sweet things. I shall place
a piece of rock opal on the table in your working -room; and if
on fine days you will sometimes dip it in water, take it into sun-
shine, and examine it with a lens of moderate power, you may always
test your progress in sensibility to color by the degree of pleasure it
The opal is indeed one of the most fascinating of gems; yet often
elusive, and at times disappointing. Of its freaks and foibles strange
stories are told. Gems of brilliant quality sometimes lose their hues
never to regain them, and others previously dull and lusterless become
radiant. Professor Egleston, of New York City, once related that
a bottle of cut opals given him by a prominent jewelry firm because
they had lost their color, after remaining in his cabinet for a time
regained their brilliancy and retained it. But to have opals regain
their color is, unfortunately, far less usual than for them to lose it.
The gem often exhibits brilliant colors when wet either with water
or oil that disappear when it is dry. Taking advantage of this
peculiarity dishonest dealers often keep opals immersed until just
before offering them for sale. Purchasers of opals of this sort
have good reason to believe the superstition commonly attached to
the opal that it is an unlucky gem. Some authorities, however, trace
the origin of the superstition to Sir Walter Scott's novel "Anne
of Geierstein," in which the baleful influence of the opal plays a promi-
nent part; and it is stated that within a year of the publication of the
book the price of opals declined fifty per cent in the European market.
Even if the superstition did not originate in either of these ways, it was
probably from a source quite as trivial, and it should prevent no one
from enjoying the pleasure to be derived from the beauties of this gem.
Chemically, opal is oxide of silicon, with varying amounts of water,
the variation being from 3 to 9 per cent. It is, therefore, closely
allied to quartz, but differs physically in being softer and not as heavy.
Further, it never crystallizes, and is soluble in caustic potash, which
quartz is not. It is infusible, but cracks and becomes opaque before
the blowpipe. In sulphuric acid it turns black, on account probably
of the organic matter it contains.
Its hardness is sometimes as low as 5.5, though generally 6. Its
specific gravity is from 1.9 to 2.3. On account of its relative softness
a cut opal often does not retain its polish well, and requires frequent
smoothing. Opals, when first taken from the ground, are often softer
even than the above, and for this reason it is usual and desirable
to allow them to harden, or " season," as it is called, for some time
after quarrying before they are polished.
Opal, as a mineral, is quite common, so that no one need suppose
because he has specimens labeled " opal " in his collection that he has
as many precious stones. It occurs in many varieties; and, especially
if it contains foreign matter, in many colors. Nearly all silica deposited
by hot waters is in the form of opal, so that the geysers of Yellowstone
Park build up cones of opal and fall into opal basins. This particular
form of opal is known as geyserite, and it is often differently colored
by different ingredients.
Wood is often preserved by silica in the form of opal, the siliceous
waters taking away the wood and replacing it by opal, grain by grain,
with such delicacy and accuracy that the structure of the wood is per-
fectly maintained. The minute shells which diatoms make consist
of opal, and when these dead shells accumulate to form deposits
of some extent we call the powdery substance tripoli, and use it for
polishing silverware and other metals. Other varieties of opal include
hyalite, a variety looking like transfixed water, so clear and colorless
is it; hydrophane, a translucent variety which sticks to the tongue and
becomes nearly or quite transparent when soaked in water ; cacholong,
a porcelain-like variety ; and menilite, a concretionary variety.
Common opal varies from transparent to opaque, being most often
translucent, and sometimes exhibiting the peculiar milkiness of color
which we call opalescence. It has sometimes a glassy, but often a waxy,
luster, the latter when pronounced giving rise to the varieties known
as wax opal and resin opal. When opal has the banded structure
of agate it is known as opal-agate ; when it has the color of jasper,
as jasper-opal; and when that of chrysoprase, as prase-opal. But none
of these varieties is used in any quantity as gems. This distinction
is reserved almost wholly for the variety known as noble or precious
opal. This is opal which exhibits a play of colors. No essential chem-
ical or physical distinction between noble opal and other varieties
is known. In a large vein of opal portions will exhibit the play
of colors and the remainder will not; but why the difference has not
yet been determined. The uncolored opal is known by the Australian
miners as "potch," while that which is precious is known as "colors."
The origin of the varied coloring, i. e., the iridescence, is not positively
known. Some regard it as due to interspersed layers containing differ-
ent percentages of water, which break up the rays of light somewhat
as a prism does, while others think that minute cracks and fissures
through the stone furnish surfaces from which the rays are reflected
in different colors back to the eye. Some opals which are dull and
lusterless when dry, exhibit considerable play of color when immersed
in water, and this fact seems to favor the first theory of the cause
of the iridescence, but the subject is not understood. The character
of the play of colors differs in different opals, and this gives rise
to different varieties. The true noble opal has the color quite uni.
formly distributed. When the color appears in flashes chiefly of red
and yellow, the stone is known as fire opal; of blue, as girasol; apd
chiefly of yellow, as golden opal. When the patches of color are small,
angular, and uniformly distributed the stone is called harlequin opal, and
if these are long and somewhat parallel, flame opal. These colors
are not, of course, inherent in the stone, its color varying from color-
less to opaque - white. The black opals sometimes seen are usually
of artificial origin, being made by soaking ordinary opals in oil and
then burning the oil. The brilliancy of the stone is thus increased ; but
it is made fragile and liable to lose color. Any opal, however, may
lose its play of colors on being heated too highly. It is the variety
and brilliancy of the changing colors which give to opal nearly all its
desirability as a precious stone, for the qualities of hardness, trans-
parency, and rich body color, which give to most other gems their
value, are lacking in it. But, together with the beauty of its changing
colors, opal possesses an advantage over all other gems in that it can-
not be successfully imitated. It is said that the Romans were able to
make artificial opals closely resembling the real ; but the art has never
been fully recovered, and we may hope it never will be. Hence, however
much danger there may be in buying an opal that has not been properly
" seasoned," or one that may lose its play of color, the purchaser may
at least be sure he has an opal and not an imitation. The stones are
usually cut in the cabochon form, this cutting being found to bring out
their brilliancy better than any facetted form. The brilliancy of the
stone may be increased in setting by giving it a backing of mother-of-
pearl, or black silk. When a number of opals are placed together they
seem to borrow brilliancy from one another, a fact which is taken ad-
vantage of in settings by placing a number together, and also by opal
dealers to dispose of inferior stones by grouping them with good ones.
For this reason when opals are purchased they should be examined sep-
arately. The value of opals depends almost wholly on the brilliancy of
their coloring and their size. Stones without the play of colors are prac-
tically worthless, while stones of ten to twenty carats' weight, with bril-
liant coloring, may bring several hundred dollars. The most highly
valued opals have long come from the mines oj: Czernowitza, in northern
Hungary. These opals are often known as Oriental opals, from the fact
that in early days they were first purchased by Greek and Turkish mer-
chants, and by them sent to Holland. There are, however, no known
localities in the Orient where precious opals are found. The rock in
which the Hungarian opals occur is eruptive, and of the kind known
as andesite. It is considerably decomposed, and the opal occurs in clefts
and veins. There is little doubt that it was from these mines that the
Romans obtained the opals known to them, and the output has been quite
constant since. It is said that the Hungarian opals are less likely to
deteriorate than any others. Still the danger of deterioration is not great
in any opal. The other important countries from which precious opals
are obtained, are Mexico, Honduras, and Australia. The Mexican opals
are mostly of the fire opal variety. They are mined in a number of the
States of the Republic Queretaro, Hidalgo, Guerrero, Michoacan, Jalisco,
and San Luis Potosi. The oldest mines are in the State of Hidalgo,
near Zimapan, where the opal occurs in a red trachyte. Most of the
Mexican opals on the market at the present time, however, come from
the State of Queretaro, where mining for them is conducted on an
extensive scale. The opal here occurs in long veins, in a porphyritic
trachyte, and is mined at various points. The stones are cut and
polished by workmen in the city of Queretaro, who use ordinary grind-
stones and chamois skins for the work, and are said to receive an aver-
age wage of twenty-three cents a day. The ^Honduras opals reach
foreign markets but rarely and usually uncut. The mines are chiefly in
the western part of Honduras, in the Department of Gracias, but good
opals also occur in the mountains on the boundary between Honduras
and San Salvador. They are little worked, but there is no doubt that
extensive deposits exist which might afford a good supply of gems if
they were properly exploited. The Australian opals come from several
localities, the most prominent at the present time being White Cliffs,
New South Wales. The matrix is a Cretaceous sandstone, which has
> y/ , s **?;f* C * -
Opal mines, White Cliffs, New South Wales
been permeated by hot, volcanic waters. Shells, bones, and other fossils
are found here entirely altered to precious opal, making objects of great
beauty. In 1899 opals to the value of $650,000 were sold from this
single region. There is no doubt that the present popularity of the
opal is due to some extent to the supply of beautiful stones which has
come from these mines, at prices one-third to one-tenth those of the
Hungarian stones. Other localities in Australia whence precious opals
are obtained are places on the Barcoo River and Bulla Creek, Queens-
land, and occasional finds in West Australia.
No localities in the United States yielding precious opals in any
quantity have yet been discovered. Some good stones have been cut
from an occurrence in Idaho, and some other minor finds have been
made, but they possess little commercial importance at present.
Opal does not seem to have been extensively known or used by
the ancients, although the Romans prized it highly, and ascribed to it
the power of warning against disaster. They named it the Paideros, or
Cupid, and regarded it the perfection of beauty. Pliny describes it as
combining the fire of the ruby, the purple of the amethyst, and the sea-
green of the emerald, all shining together in an indescribable union.
The Roman senator Nonius owned one set in a ring, which was said to
be valued at nearly a million dollars. History records that for refusing
to sell the stone to Mark Antony he was sent into exile. This stone was,
however, no larger than a hazelnut, and would probably be worth hardly
a hundred dollars at the present day. The next most famous opal in
history is one that was owned by the Empress Josephine, and called
"The Burning of Troy," on account of the brilliancy of the flames
which shot forth from its depths. The present whereabouts of neither
of these gems is known. A large Mexican opal, now in the Field
Columbian Museum, is carved in the image of the Mexican sun-god,
and has a setting of gold representing the diverging rays of the sun.
This gem is very ancient, and is believed to have been kept in a Persian
temple. To the opal was assigned, in the sixteenth century, the power
of making its wearer a general favorite, enhancing the keenness of his
sight, and shielding him from suicide. The name opal is from the Greek
word for eye, and shows the esteem in which the gem was held for treat-
ing diseases of that organ. It was also supposed to have the virtues of
all the stones whose colors it showed. It was believed to stimulate the
heart, cheer the despondent, and preserve from contagion. Like the tur-
quois, its color was supposed to change if its wearer grew ill, and regain
it when he recovered. It symbolized hope also. The belief in its bring-
ing ill-luck is of more modern origin, and confined to Occidental peoples.
Possession of a black opal is regarded in India, at the present time, as
productive of good fortune.
Jade is a term applied in general to a tough, fibrous mineral of a
greenish color having the composition of a pyroxene or amphibole.
Until recently the mineral was supposed to form a single species, but
it is now known that at least two species are grouped under this title.
One of these is a form of pyroxene, and is known as jadeite, the other
is a form of amphibole, and is named nephrite. Further, the term is
often used to include any tough green stone having a hardness between
6 and 7 and taking a good polish, since such rocks or minerals are often
carved by people who use true jade. Jadeite is a mineral of definite
composition, it being a silicate of soda and alumina. The percentage
composition of pure jadeite is. silica 59.4 per cent, alumina 25.2 per
cent, and soda 15.4 per cent. Its hardness is a little below that of
quartz, or between 6.5 and 7, but its extreme toughness makes it often
seem harder than this. It is a rather heavy mineral, its specific gravity
being 3.35. In color it varies from nearly white to nearly emerald-green.
The white varieties sometimes contain spots of bright green, supposed to
be due to chromium. The mineral does not crystallize, but is known from
its optical properties to be either monoclinic or triclinic. It does not
occur transparent, but has a peculiar translucency or subtranslucency not
unlike that of horn or fine porcelain. It has a fibrous to granular
structure readily seen under the microscope, and a splintery fracture. It
is very tough. Jadeite fuses readily before the blowpipe to a trans-
parent, blebby glass, and colors the flame yellow, thus differing from
nephrite, which is almost infusible. The term chloromelanite is applied
to a dark green to black jadeite containing considerable iron.
Objects of jadeite carved in prehistoric times are found abundantly
in Europe, Asia, America, and Africa, but only a few of the original
localities whence it was obtained are now known. ^The most important
locality known at the present time is in Upper Burmah in the vicinity
of Mogoung. The jadeite occurs in boulders embedded in a reddish
yellow clay in the valleys of tributaries of the Dschindwin River. The
boulders are mined by digging shallow pits after the fashion of the Bur-
mese miners, as many as a thousand men often being employed in this
work. The miners break the boulders by heating, and when pieces of
quality suitable for cutting are found, they are either laid aside to sell to
caravans which come to the mines for this purpose from China, or are
turned over to native artisans, who reduce them to desired shapes by
sawing them with steel wire strung on a bamboo bow. The jadeite
from this locality is commercially distributed all over China, where it is
held in high esteem, and commands a high price. Bauer states that he
saw a piece containing less than three cubic feet which was valued at
$50,000. The jadeite of milk-white color is that most highly esteemed,
although that with bright green spots is also considered of superior value. /
Nephrite is a variety of amphibole much resembling jadeite in color,
hardness, and texture. It is, however, of somewhat lower specific gravity
than jadeite, ranging as it does from 2.96 to 3.1, and it fuses with much
greater difficulty. Under the microscope a section shows a finely fibrous
character differing from that of the broad fibers or granules of jadeite,
and the optical characters throughout are those of an amphibole rather
than of a pyroxene. In composition nephrite is a silicate of calcium and
magnesium, having the theoretical percentages, silica 57.7, magnesia 28.9,
and lime 13.4. A little alumina, iron, and soda are often found combined
with the above. Nephrite has the glistening luster and semi-translu-
cency of jadeite, and like that mineral breaks with a splintery fracture.
It is not attacked by acids. It does not occur in distinct crystals.
<^The most important locality for nephrite at the present time is
Turkestan, where it occurs in the Karakash Valley in the Kuen Lun
Mountains, and at other points in the same range. In these localities it
forms layers in gneiss and amphibole schists. It is very pure and trans-
lucent. Some of the mines have been worked for over two thousand years.
//Nephrite of excellent quality also occurs in eastern Siberia in the
beds of the Onot and Chara Jalga rivers. It occurs here as boulders,
one of which is described as being twelve feet in length and three feet
in width; it is also found in place. A canopy thirteen feet in height
has been made for the tombs of the present Czar and Czarina of Russia
of nephrite from this locality.
In New Zealand nephrite occurs in seve^l localities on the west coast
of South Island, and is used extensively by the Maoris for fashioning into
weapons and ornaments.
Boulders of nephrite have also been found in river beds in Alaska.
In several river beds of Europe nephrite is found as pebbles, and it occurs
in place in the Zabten Mountains in Silesia, but none of these localities
affords an important source of supply.
Jade, including both jadeite and nephrite, though still highly prized
by the Chinese and other peoples of Asia, is little used by Europeans at
the present time. Among early man, however, in Europe, Asia, America,
and Africa, the use of jade seems to have been well-nigh universal. Orna-
ments and utensils of this stone are found among the remains of the lake
dwellers of Switzerland, the ancient peoples of France, Mexico, Central
America, Greece, Egypt, and Asia Minor. The remarkable similarity
in the material from which these objects are made, as well as their
resemblance in form, has led some authorities to conclude that they
came from a single region, and indicate a migration of people from one
locality and a commerce in this stone. If the evidence to this effect
were sufficiently convincing it would make possible many deductions
regarding the peopling of the globe of which we have as yet little certain
knowledge. Those who oppose the view of the distribution of jade from
a single source declare that the stone was found in each different coun-
try, and was similarly selected at a certain stage in the development of
each people. This view seems to be supported by the fact that the
so-called jade objects of different peoples are not composed exclusively
of the two minerals above mentioned, but include any stone having about
the same physical characters and color. Still, the two minerals jadeite
and nephrite largely predominate. The two are equally used by the
Chinese of the present day, who do not seem to distinguish between them.
Their name for jade is Yu, or Yu-shih (Yu-stone). In general it has been
found that the peoples nearer the equatorial zone of the earth use more
jadeite, and those nearer the poles more nephrite, but whether this use
is anything more than accidental cannot be said.
The name jade is from the Spanish piedra de hijada, " stone of the
loins," and was given by the Spaniard Monardas in 1565 to the jade
brought from Mexico and Peru because these stones were reputed to be
of value in kidney diseases. For this purpose it was much worn as an
amulet, or taken internally. The name was given the Latin form lapis
nephriticus by Clutius in 1627, and hence comes the word nephrite.
Jade is also called ax-stone because of the amount of it used in making
The Aztecs applied the name chakhihuitlio a greenish stone which
they used extensively and prized highly. This in some instances proves
to be jade and in others turquois. It is probable that much of the
so-called emerald of ancient writers and historians, both of Europe and
America, was jade.
This variety of pyroxene affords transparent green stones, which, may
resemble in color chrysolite or green tourmaline. Diopside is common as
a rock-forming mineral, but is obviously of use for gem purposes only
when occurring in large, transparent crystals. The three localities where
material of the latter sort is chiefly obtained are the Ala Valley in the
Piedmont region of Italy, the Zillerthal in the Tyrolese Alps, and De
Kalb, St. Lawrence County, New York. The first and third localities
afford light green stones, the second those of a dark bottle-green color.
They are cut generally as brilliants, and while not extensively used, make
satisfactory stones. Those obtained from De Kalb afford gems up to 10
carats in size. Diopside may be distinguished from gems of other min-
erals of the same color by its lack of dichroism, this being a characteristic
of this pyroxene. From glass it differs in being doubly refracting.
Its system of crystallization is monoclinic. Its hardness is 6 ; specific
gravity, 3-3.6. In composition diopside is a silicate of lime and mag-
nesia, with a small amount of iron, its color growing darker with more
iron. It has a prismatic cleavage, not often strongly enough developed,
however, to interfere with cutting the mineral. Its luster is somewhat
oily like that of chrysolite. The appearance of crystals from the Ala,
accompanying essonite, is shown in the colored plate.
HYPERSTHENE AND BRONZITE
These minerals, belonging to the pyroxene group, are employed in
jewelry when, on account of a fibrous structure or a regular arrangement
of inclusions, they exhibit a chatoyant effect. They do not afford trans-
parent stones, but are cut en cabochon to make cat's-eyes and give other
The color of hypersthene is usually a dark bronze, so opaque as to
approach a metal in luster. The light which plays over it is copper-red in
color, and very brilliant in a good stone. The cause of the chatoyancy
is supposed to be countless crystals of the oxide of titanium, known as
brookite, which are arranged in regular order in the stone. The stone
must be cut with reference to the direction of these in order to give the
The hypersthene used for this purpose comes almost exclusively from
the Island of Paul on the coast of Labrador. Here it occurs together
with labradorite as shore pebbles, and it may also be quarried from neigh-
boring cliffs. For cutting, a sound piece without flaws must be used,
and it is often necessary to break a number of fragments before a suit-
able one can be found. Yet the supply of material is so abundant and the
demand comparatively so limited that the stones do not command a high
The hardness of hypersthene is 5-6; its specific gravity 3.4-3.5. It
fuses before the blowpipe to a black enamel, and is partially decomposed
by hydrochloric acid. Its name comes from two Greek words meaning
very tough. It is a common constituent of eruptive rocks, usually in
small crystals. Its system of crystallization is orthorhombic. In com-
position it is a silicate chiefly of iron and magnesium.
Enstatite resembles hypersthene in composition and properties, and
its limited use in jewelry is to furnish " cat's-eyes " of a green color. The
chatoyant effect is due usually to a fibrous structure. The principal
locality for this variety is near Harzburg in the Harz. Schillerizing
bronzite is found in a few localities in this country.
This mineral differs from nearly all others held in favor as gems
in not being transparent, and never-' occurring in the form of well-
defined crystals. In composition turquois is a hydrous phosphate of
aluminum, the percentages being: water, 20.6 per cent, alumina, 46.8
per cent, and phosphorus oxide, 32.6 per cent. Thus, in composition
as well as opacity, turquois differs from most other gems, they being
usually silicates, or some form of silica. Besides the above ingredients
turquois always contains a small percentage of copper oxide, and usually
iron, calcium, and manganese oxides in small amount. It is the copper
compound which undoubtedly gives turquois its inimitable color, that
color to which it owes its chief charm as a gem. This color varies from
sky-blue through bluish green, and apple-green to greenish gray.
Of these colors, the pure sky-blue, or robin' s-egg blue, is by far
the most highly prized, and is, in fact, the only standard color for the
gem. Green is, however, the most common and the most lasting color
of the mineral, and it is one of the faults of the gem that the blue
shades often fade to green after being exposed to the light for a time.
In a stone of first quality, however, especially a Persian turquois, such
fading of color is exceptional. The hardness of turquois is 6. It is, therefore,
somewhat more easily scratched than other gems. Its specific gravity
varies from 2.6 to 2.8, being about that of quartz. It does not fuse
before the blowpipe; but turns brown and assumes a glossy appear-
ance. By the copper of the turquois the blowpipe flame is usually
colored green. When heated in a closed glass tube the mineral turns
brown, or black, and gives off water. Almost any of these tests will
serve to distinguish true turquois from stones used to imitate it. It
has a conchoidal fracture and waxy luster. On account of its opacity
it is almost never cut with facets, but in a round, or oval form, with
convex surface. The pieces desirable for cutting rarely reach a large
size, so that big gems of turquois are comparatively unknown.
Much of the so-called turquois used in former times was bone-turquois,
or odontolite, made from fossil bone, colored by a phosphate of iron. It
is still obtained mostly from the vicinity of the town of Simor, Lower
Languedoc, France. It is sometimes known as Western, or Occidental
turquois, in distinction from the Oriental turquois, most of which came
originally from Persia. Odontolite does not retain its color by artificial
light, as does true turquois, and may be further distinguished by giving
off an offensive odor when heated, owing to decomposition of animal
matter. Further, it is lighter than true turquois, and does not give
a blue color, with ammonia, when dissolved in hydrochloric acid, as does
tx The finest turquoises have long come from Persia, from a locality
not far from Nishapur, in the province of Khorassan. Here the min-
eral occurs in narrow seams, in the brecciated portions of a porphyritic
trachyte and the surrounding clay slate. There are several hundred
mines in the region, and the entire population of the town of Maaden
derives its livelihood from mining and cutting the stones. It is said
that $40,000 worth of stones are taken from these mines annually.
A pound of stones of the first quality sells at the mines for about
$400, and is worth more than double that price in Europe. The mines
must be very ancient. A description of them written in A. D. 1300
is known ; and according to a tradition current in the region one of the
mines, known as Isaac's mine, was opened by Isaac the son of Abra-
ham. There are other turquois mines in Persia, but their product
is comparatively small. Other Oriental localities from which gem
turquoises are obtained are Sinai, in Arabia; the Kirgeshi Steppes,
in Siberia; and the Kara-Tube Mountains, in Turkestan. Egypt also
furnishes large quantities of turquois, which does not, as a rule, retain
its color well. I/
Turquois is not an uncommon mineral in the United States, and
many gems of fine quality have been obtained from mines within our
borders. The oldest and best known mines are those at Los Cerrillos,
New Mexico. This locality was long worked by Indians and Spaniards,
as shown by the great extent of the excavations. There are pits to be
seen here two hundred feet in depth, and piles showing that thousands
of tons of rock have been broken out. Fragments of Aztec pottery,
vases, cooking utensils, stone hammers, etc., are found at the mines,
and trees of considerable size have grown over the once worked portions.
Hence, the beginning of the mine workings must date back at least prior
to the discovery of America. The mines were worked more or less
by Spaniards in the early part of the seventeenth century with the
consent of the Indians, or at least without hindrance from them. In
1680, however, a large landslide occurred on the mountain at the
mine, and many of the Indian miners were overwhelmed. Believing
the Spaniards to be in some way responsible for the accident, and
perhaps fearing that their gods were displeased, the Indians rose in their
might and expelled the Spaniards from the region. The Indians seem to
have prized the turquois highly as an ornament, rudely polishing it, and
using perforated pieces like the one shown in the accompanying colored
plate for necklaces. They also decorated their idols and other objects
of worship with pieces of turquois. The mountain at which the
Los Cerrillos turquois mines occur is called Mount Chalchihuitl, in allu-
Gem Turquois and Copper Co., Burro Mountain, near Silver City, New Mexico
sion to an Indian name that is supposed to have been applied to tur-
quois. The mountain is evidently of volcanic origin. The color of most
of the turquois from this locality is apple -green rather than the
highly prized blue, but some gems of a good blue have been obtained.
Kunz, writing in 1890 of the sale of gems from this locality, says that
the Indians usually dispose of them at the rate of twenty-five cents for
the contents of a mouth, which is where they usually carry them.
Several other localities in New Mexico are worked for turquois. In
Cochise County, Arizona, is a locality known as Turquois Mountain,
where considerable mining is carried on. ' Turquois is also mined in Gila
County, Arizona ; Lincoln County, Nevada ; and San Bernardino County,
California. Several of these localities have been opened up recently,
the present popularity of the gem perhaps having stimulated its output.
Good New Mexico turquoises are quoted at $5 to $6 per carat at the
The much higher price commanded by turquois of a blue color has
led to a counterfeiting of this color by staining green turquois or other
stones with Prussian-blue. Kunz describes a method of detecting this
stain which consists in washing the stone with alcohol ; and after wiping
it, to remove any grease, laying it for a moment in a solution of am-
monia, when the blue color, if artificial, will largely disappear.
At how early a date turquois began to be prized as a gem is not known.
The word turquois is a French word meaning Turkish, or a Turkish gem,
and came to be applied because the gem was introduced into Europe
by way of Turkey. It is probable that the gem has been in use from
the remotest past among Oriental peoples, and it is certainly still highly
prized by them. Not the least of the reasons for which it is held in
high esteem by them, as well as by many Occidental individuals, is the
good fortune it is supposed to bring to its possessor. One of the prov-
erbs of the Orientals is, "A turquois given by a loving hand carries
with it happiness and good fortune." That belief in the turquois as an
agent of good luck was current in Shakespeare's time is shown by the
grief which he represents Shylock as suffering over the loss of his
turquois ring. Numerous other superstitions cling around the turquois.
One of these, due probably to slight changes of color which the stone
may undergo under certain climatic influences, is that if the owner of a
turquois sickens it will grow pale, and at his death lose its color entirely ;
but it will regain its color if placed on the finger of a new and healthy
master. It was supposed to show the presence of poisons by sweating
profusely. It is still used in the East as a remedy for dyspepsia, hernia,
insanity, and cancerous sores Worn as an amulet, it is supposed to
bring happiness, dispel fear, and render its wearer safe from drowning,
lightning, and snake bite. In Egypt it is used to cure cataract if set in
a silver ring, dipped in water, and applied to the eye with proper incan-
tations. In Germany it is hi favor for engagement rings, owing to the
belief that if either party prove inconstant the stone will make the
fickleness known by weakening in color. It is curious that of the two
non-crystallized gems, turquois and opal, one should be considered lucky
and the other unlucky. Both are more liable to changes of color than
other gems, and this fact has probably led to the ascription of good
or ill fortune to them.
Variscite resembles turquois in many properties, being, like that min-
eral, an opaque, hydrous phosphate of aluminum not occurring in
distinct crystals. Its color is, however, normally an apple-green to emer-
ald-green rather than blue, and its luster is more nearly vitreous than
that of turquois. Its hardness is not equal to that of turquois, being
but 4. Its specific gravity is 2.4. It is infusible before the blowpipe,
but becomes white and colors the flame deep bluish-green on heating.
The only form of it that has been used to any extent for gem purposes
is one found in Cedar Valley, Tooele County, Utah. This is of a bright
green color, and occurs as nodules in a crystalline limestone. Pieces of
this give a pleasing effect when employed in jewelry in a manner similar
This mineral has been found only in a Celtic grove at Mani-er-H'rock,
near Lockmariaquer, in Brittany. It is there preserved in the form of
rounded pieces in size between a flaxseed and a pigeon's egg, and was
doubtless employed by the ancient Celts as an ornamental stone. Where
they obtained it has never been learned. It is a hydrous phosphate of
aluminum of a green color, spotted with whitish and bluish. Its hard-
ness is 3.5 to 4 ; specific gravity 2.5. It is opaque to translucent. On
account of its historic (or prehistoric) interest pieces have been cut and
used to some extent in jewelry ; but its employment can obviously not
be extensive on account of the small amount known. The name cal-
lainite comes from callais, a precious stone mentioned by Pliny, the exact
nature of which is not known, although it is generally supposed to have
Amazonstone, crystallized (Colorado).
Labradorite, polished (Labrador).
Aniazonstone, crystallized (Colorado).
Labradi trite, polished (Labrador).
Moonstone, polished Norway).
Feldspar is the family name of several minerals closely related, and
indeed grading into each other, but distinguished by mineralogists by
separate specific terms. These minerals are all silicates of aluminum,
with some alkali or alkali earth, having a hardness of about 6 and a
specific gravity varying from 2.5 to 2.7. They are fusible with difficulty
before the blowpipe, crystallize in the monoclinic or triclinic system, and
cleave in two well-marked directions nearly or quite at right angles to
each other. It is this latter property, probably, which led to the group-
ing of these minerals as spar, since this term is applied in common lan-
guage to any minerals which break with bright crystalline surfaces. The
term field spar, of which feldspar is probably a corruption, was perhaps
given the minerals of this group because of their widespread occurrence.
The English spelling of the word is felspar. The feldspars form an essential
part of nearly all eruptive rocks, and by their decomposition produce clays
and other soils which may harden into great areas of sedimentary rocks.
They are thus of great geological importance and interest. Usually the
white crystals to be seen in an eruptive rock in contrast to the dark
green or black of the pyroxene or hornblende, or the glassy, nearly
colorless quartz, are feldspar. The feldspar may, however, contain more
or less iron, and then take on a flesh color or become even darker. Feld-
spar crystals can best be recognized by their prominent cleavage, which
appears as numerous bright flat surfaces extending in any given crystal
in the same direction. The crystals, while they may be of so minute
dimensions as to be visible only with the microscope, may, on the other
hand, reach in veins in coarse-grained granites a length of a foot or more.
As ornamental stones only certain varieties of feldspar are valued,
and their value depends on accidents of color or structure. The first of
the feldspars which may be mentioned as being prized as an ornamental
stone is amazonstone, or green feldspar. This in composition is what is
called a potash feldspar, potash being the alkali which in combination
with alumina and silica goes to make up the mineral. The percentages
of each in a pure amazonstone are, silica 64.7, alumina 18.4, and potash
16.9. The mineralogical name of the species is microcline, meaning
small inclination, and refers to the fact that the angle between the two
cleavages of the mineral is not quite a right angle. The common color
of microcline is white to pale yellow, but occasionally green and red occur.
It is only to the green variety that the name of amazonstone is
applied, a name meaning stone from the Amazon River. It first referred
probably to jade, or some such green stone from that locality, and then
came to include green feldspar. No occurrence of green feldspar in that
region is now known.
Practically all the amazonstone now used for ornamental purposes
comes from three localities. These are the vicinity of Miask in the Ural
Mountains, Pike's Peak, Colorado, and Amelia Court House, Virginia.
In all these places the amazonstone occurs in coarse-grained granite, and
is accompanied by quartz and mica. All gradations are found in color
from the deep green to white, only the bright green being prized for
ornamental purposes. The feldspar is usually well crystallized, and
crystals of several pounds' weight may be found. A crystal will rarely
be of a uniform color, streaks of paler green or white being commonly
present. Only the uniformly colored portions are prized for ornamental
purposes. The green often takes on a bluish tone, and blue sometimes
even predominates. The color is doubtless due to some organic matter,
as it disappears on heating, leaving the stone white. The stone is always
opaque. Its use is not extensive, its sale being chiefly to tourists in
the vicinity of the regions where it is found. Several other localities in
the United States besides those mentioned afford the mineral, though not
in large quantities. It occurs in two or three localities in North Caro-
lina; in Paris, Maine ; Mount Desert, Maine; Rockport, Massachusetts ;
and Delaware County, Pennsylvania. The finest comes from the Pike's
Peak locality. Kunz states that when crystals from the latter locality
were first exhibited at the Centennial Exposition in Philadelphia, in
1876, they were a great surprise to Russian dealers, who had brought
over some amazonstone from the Urals, expecting to sell it at what
would now be considered fabulously high prices.
The second species of feldspar which may be mentioned as of use as
an ornamental stone is labradorite. This differs in composition from
amazonstone in containing soda and lime in place of potash, the percent-
ages in a typical labradorite being, silica 53.7, alumina 29.6, lime 11.8,
and soda 4.8. Labradorite has the typical cleavage of feldspar and
cleavage surfaces in the direction of easiest cleavage are usually marked
by rows of parallel striae. These show that the mass is made up of a
series of crystal twins in parallel position, and afford an excellent crite-
rion for determining a triclinic feldspar. Labradorite is a common
rock-forming mineral, especially in the older rocks. It is only, how-
ever, when it occurs in large pieces which exhibit a play of colors that '
it is prized as an ornamental stone. The labradorite exhibiting the latter
property in the most remarkable degree and hence most valued is that
found on the coast of Labrador near Nain, and the adjacent Island of
St. Paul. It was first found here by a Moravian missionary named Wolfe,
and brought to Europe in the year 1775. It occurs together with hy-
persthene, in a coarse-grained granite, or perhaps a gneiss. From these
it is weathered out by wave and atmospheric action, and occurs as beach
pebbles. It is also mined from veins. Labradorite of pleasing color and
opalescence occurs in a few localities in Canada, and in Essex County, New
York. Two localities occur in Russia, one near St. Petersburg, and the other
in the region of Kiew. The labradorite of the latter locality is the better,
its occurrence being in a coarse-grained gabbro. The Labrador occur-
rence exceeds all others, however, in abundance and beauty, and by far
the larger quantity used in the arts comes from there. The play of
colors which gives labradorite its attractiveness is rarely seen to advan-
tage except upon a polished surface, but whether polished or unpolished,
it only appears when the surface is held at a particular angle with refer-
ence to the eye. Emerson thus describes it in his essay on " Experience,"
" A man is like a bit of Labrador spar, which has no luster as you turn it
in your hand, until you come to a particular angle ; then it shows deep
and beautiful colors."
The play of colors seen in labradorite is not like that of the opal,
which presents to the eye fragments of different colors varying in differ-
ent positions, but appears as broad surfaces of a single color. It is only
rarely that these colors change with a change of position. The colors
over any given surface are not usually alike, but more than two or three
tints are rare. Each tint is uniform where it occurs, but a tinted surface
may be interspersed with many spots exhibiting no sheen. Both colored
and uncolored portions have only vague outlines, and merge into each
other at the edges. Bauer mentions a labradorite from Russia the col-
ored portions of which formed a striking likeness of Louis XVI., the
head being a beautiful blue against a gold-green background, while above
appears a beautiful garnet-red crown. Excellent effects are sometimes
produced in labradorite by cutting it in the form of cameos so as to
make the base of different color from the figure in relief. Because of its
chatoyancy labradorite is sometimes known as " ox-eye," or " ceil-de-bceuf."
Of the different colors shown by labradorite blue and green are
most common, yellow and red least so. These colors are regarded by
Vogelsang as of different origin, the blue being, in his opinion, a polariza-
tion phenomenon due to the lamellar structure of the feldspar, and the
yellows and reds the result of the reflection of light from minute
included crystals of magnetite, hematite, and ilmenite.
The gems known as moonstone and sunstone owe the play of colors
which gives them their respective names to similar causes. These gems
are generally some form of feldspar, although any mineral giving a
similar sheen of color might be included under them. The moonstone
of commerce comes chiefly fromkCeylon, where it occurs in large pieces
the size of a fist in a clay resulting from the decomposition of a por-
phyritic rock. Pieces of these when polished exhibit a beautiful pale
blue light coming from within, which makes the stone prized as a gem.
The cause of this light has usually been thought to be reflection from
minute tabular crystals lying in parallel position in the stone. It seems
to be partly caused also by absorption of red and yellow rays by the stone,
leaving the violet and blue to be reflected and diffused.
Moonstone varies from translucent to opaque, and from colorless to
white, the essential feature being the blue opalescent light or chatoyancy
exhibited from a polished surface. Good feldspar moonstones are worth
from three to five dollars a carat.
The Ceylon moonstone is sometimes known as Ceylon opal, but it
is not opal. On the contrary, it is the variety of feldspar known as
orthoclase, which is a potash feldspar, differing from the microcline
just described in being monoclinic in crystallization and in having two
cleavages meeting at right angles. Another species of feldspar used as
, moonstone is albite. This is a soda feldspar, and is triclinic, but exhibits
the chatoyancy characteristic of moonstone. One variety is known as
peristerite, from the Greek word for pigeon, and is applied on account
of the resemblance of the sheen to that of a pigeon's neck. It is found
t^at Macomb, St. Lawrence County, New York. Albite found at Mineral
Hill, Pennsylvania, also exhibits the chatoyancy of moonstone. Amelia
Court House, Virginia, is another locality whence come pieces either of
orthoclase or oligoclase exhibiting this property. Like most of the more
or less opaque gems, moonstone is cut chiefly in the cabochon form. It
is of late, however, cut in the form of balls, which are quite popular, the
bringing of good luck being attributed to them. The brilliancy of moon-
stone is considerably increased by mounting it against black.
In the Middle Ages carrying a moonstone in the mouth was believed
to be an aid to the memory. It was prescribed in cases of epilepsy,
either as an amulet or powder. Belief in its efficacy for this purpose still
persists among the Basques. During the period of increase of the moon
it was regarded a potent love charm, while during the decrease of that
luminary it was supposed to enable its wearer to foretell the future.
Sunstone is the term by which those kinds of feldspar are known
which reflect a spangled yellow light. The appearance comes from minute
crystals of iron oxide, hematite, or gothite, which are included in the
stone, and which both reflect the light and give it a reddish color. Like
labradorite the sheen is visible only when the stone is held at a certain
angle. The sheen of sunstone is best visible when the stone is held in the
sunlight or strong artificial light. The variety of feldspar to which the
sunstone most in use at the present time belongs is oligoclase, a soda-lime
triclinic feldspar. Like labradorite, it usually exhibits on the surface of
easiest cleavage parallel striations, due to twinning structure. The best
sunstone at the present time comes from Tvedestrand, in southern Norway,
where it occurs in compact masses, together with white quartz, in veins
in gneiss. Some also comes from Hittero, Norway. In Werchne Udinsk,
Siberia, another occurrence was discovered in 1831. Previous to this
Bauer states that all the sunstone known came from the Island of Sattel
in the White Sea, and was very costly, although of a quality which would
not now be deemed desirable. At the present time, although stones of
fine quality can be obtained, sunstone is little used in jewelry, and its
market value is very low. Statesville, North Carolina, and Delaware
County, Pennsylvania, are two localities in the United States where good
sunstone has been obtained.
Both sunstone and moonstone can be accurately imitated in glass,
and the distinction of the artificial from the real by ocular examination
alone might be somewhat difficult. Glass, however, lacks the cleavage
of feldspar, and is somewhat heavier and softer. The discovery of the
method of making artificial sunstone is said to have been accidental, and
was made at'Murano, near Venice, when a quantity of brass filings by
chance fell into a pot of melted glass. The product was for a long time,
and is still, used in the arts under the name of goldstone. Sunstone is
sometimes known as aventurine feldspar, in distinction from aventurine
quartz, which presents a similar appearance, owing' to the inclusion of
scales of mica. The term aventurine is from the Italianxziwmwra,
meaning chance, and refers to the chance discovery above referred to.
Other forms of feldspar than those here described occasionally furnish
gems which are transparent and colorless, and valued for their luster.
The varieties chiefly employed in this manner, are adularia, a variety of
orthoclase which is often transparent, the best specimens being obtained
in Switzerland, and oligoclase, in the transparent form in which it is
found near Bakersville, North Carolina.
This is a natural glass which is used to some extent at the present
day for ornamental purposes. In earlier times, especially among the
prehistoric peoples of the western hemisphere, its use was very exten-
sive, both for utensils and ornamental articles.
Obsidian is a product of volcanic outflows, being produced where
a rapid cooling of certain liquid lavas has taken place. In color it
may be black, gray, green, red, brown, or yellow, and in diaphaneity
may vary from transparent to opaque. The kind used almost exclu-
sively in the arts is of black color, generally transparent only in thin
The properties of obsidian differ little from those of manufactured
glass. Its hardness is 5-5^; specific gravity 2.3-2.5. It has a vitreous
luster, and is brittle, breaking with a large conchoidal fracture which
is quite noticeable. Its extreme brittleness makes cutting of it difficult.
It fuses rather easily before the blowpipe to a porous, gray mass.
Being amorphous it cannot be distinguished optically from glass, like
which it is singly refracting. It frequently contains partially crystal-
lized inclusions, however, and gas pores, which are not common to arti-
ficial glass. When these ,are arranged in regular order the obsidian
shows a chatoyancy, or schillerization, which gives a pleasing effect.
In chemical composition obsidian shows a higher percentage of alumina
and a lower one of alkalies than artificial glass. The following is the
composition of an obsidian from the Lipari Islands: Silica, 74.05,
alumina, 12.97, iron oxide, 2.73, lime, 0.12, magnesia, 0.28, potash,
5.11, soda, 3.88, loss on ignition, 0.22. Obsidian is not easily attacked
by acids. One of the largest known deposits of obsidian in this coun-
try occurs in the Yellowstone Park, Wyoming. The locality is known
as Obsidian Cliff, and the deposit has a thickness, according to Profes-
sor Iddings, of 75 to 100 feet. There are evidences that the Indians
obtained obsidian here for use in their arts, as flaked fragments are
found in the vicinity. The color of this obsidian is for the most part
black, but shades of red and yellow occur.
A variety of obsidian, showing red and black in alternate streaks,
or spots, occurs here as well as in other localities. This is known as
marekanite, or " mountain mahogany," and makes a pretty stone, which
is used for the manufacture of some objects.
The mines from which the Aztecs and their successors seem to have
obtained the greater part of their obsidian are located in the State
of Hidalgo, Mexico, about thirty miles east of Pachuca. The locality
is known as the Sierra de las Navajas, or Hill of the Knives. Here
hundreds of acres have been worked over, and heaps and ridges of obsidian
fragments are continuous for one or two miles. The mining seems to have
Obsidian cliff, Yellowstone Park
been performed by digging pits from 6 to 20 feet in depth. Large pieces
of obsidian were thus obtained, which were shaped into so-called cores,
cylindrical pieces of varying diameters. From these, articles of the
desired shape were obtained by flaking and polishing. Immense heaps
of flakes show that working of the obsidian was carried on here for
centuries. Articles made from it are found among the Aztec ruins in
Mexico, and as far north as the mounds of Ohio. They are of great
variety, and many of them exhibit much skill in workmanship. They
include masks, ear ornaments, lip ornaments, spear heads, arrow heads,
knives, and razors. Mirrors were also made from the obsidian. To this
latter use obsidian was put by the Romans in the time of Pliny. They
also manufactured ring stones, seals, and other ornaments from it. The
source of their obsidian was probably the island of Lipari, for exten-
sive fields of beautiful obsidian are still known and worked there.
It also occurs in the neighboring islands.
Its use at the present time is chiefly for making mourning jewelry
it being preferred by some to jet. Obviously, it can be closely imitated
in glass; and though the cost of cut obsidian is small, glass is still
cheaper. The schillerizing, or chatoyant obsidian, is more highly prized
than the plain, and cut en cabochon it makes a very pretty ring stone.
Obsidian is sometimes called Iceland agate, perhaps because obtained
in Iceland, although by some it is thought that the name is a corrup-
tion of island agate, from the occurrence of the stone in the islands
of the Mediterranean.
( UNIVERSITY j
ChlorastroHte, polished (Isle Royale).
Hematite, polished (England).
Thoiusouite, polished (Lake Superior).
Cat's-eye, Quartz, polished (Ceylon).
Variscite, polished (Utah).
Moldavite, cut (Bohemia).
Thomsonite, rough (Lake Superior).
This term is applied to a transparent green stone found occurring
in small pieces in Bohemia, in the region drained by the river Moldau,
whence the name moldavite. The color of the stone is of the peculiar
character generally designated as bottle-green; and since its physical
characters, such as hardness, fracture, optical qualities, etc., also resemble
those of glass, the view was long held that the fragments found were
remains from some long since demolished glass works. Latterly, however,
Moldavite pebbles as found
Dr. Franz Suess has advanced the opinion that the fragments are of extra-
terrestrial origin, and represent a peculiar kind of meteorite. These
views he has set forth in an elaborate work upon the subject.
Proof of such an origin of moldavite would lend an added interest
to it, and probably increase its use for jewelry, the present employ-
ment of it being rather limited. The pieces as found are waterworn
pebbles of various shapes, usually with deeply indented or pitted sur-
faces, as shown in the accompanying cut. In size they are never
larger than one's fist, while they are usually much smaller. They are
found in the beds of brooks and in the soil. Regions near Budweis
and Trebitsch are especially prolific in the pebbles. Moldavite has a
hardness not quite equal to that of feldspar, being a little less than 6.
It is thus somewhat harder than ordinary glass. Its specific gravity
ranges from 2.32 to 2.36. Unlike ordinary glass and obsidian it is
almost infusible before the blowpipe, and when fused remains perfectly
clear on cooling. It differs considerably in chemical composition from
ordinary glass, having as it does a higher percentage of silica, consider-
able alumina, and a small percentage of alkalies. The percentages of silica
range between 88 per cent and 78 per cent ; those of alumina between 5
per cent and 13 per cent ; and those of potash and soda between 1 per
and 2.5 per cent. The following is an analysis of a dark green moldavite
from Budweis: Silica, 77.75, alumina, 12.90, iron protoxide, 2.60, lime,
3.05, magnesia, 0.22, potash, 2.58, soda, 0.26, water, 0.10. In ordinary
glass the percentage of silica is not much above 50 per cent ; there is
almost no alumina, while lime and magnesia amount to about 20 per
cent, and potash and soda 20 per cent to 25 per cent.
Glassy pebbles similar to moldavite are found on the island of Billiton,
near Java. These are known as billitonite. They are also found in
Borneo and several parts of Australia. In these places they are believed
to be of volcanic origin if not meteoric.
Of these different occurrences of moldavite only the Bohemian is so
far used to any extent in jewelry. Owing to the abundance of the mate-
rial the stones cut from it are not expensive, being valued at no more
than quartz or agate. Actual glass can easily be substituted for it
with little chance of detection.
This common and widely distributed mineral occasionally affords
transparent crystals which admit of limited use in jewelry. The cut
stones cannot, however, endure much wear, as the hardness of the
mineral is only 5. The colors which the crystals may present are
violet, light blue, yellow, rose, and various shades of green. One color
and degree of transparency may characterize an entire crystal, or but
a portion of one. The crystals have nearly always the shape of a simple
hexagonal prism, the mineral crystallizing in the hexagonal system.
In composition apatite is phosphate of lime, with a small percentage
of fluorine or chlorine. It is, therefore, much like bone in constitu-
tion. It is barely fusible before the blowpipe. On moistening a frag-
ment with sulphuric acid, and heating, the flame is colored pale green
from the phosphorus present. Apatite is attacked and dissolved by
strong acids. Its specific gravity is 3.17-3.23. Its luster is vitreous
The best known transparent apatite is obtained at Ehrenfriedersdorf,
in Saxony. Here transparent crystals of a violet color occur capable
of affording cut stones of a few carats in weight. From Arendal,
Norway, greenish-blue crystals are obtained, furnishing the variety known
as moroxite. A yellowish - green variety, known as asparagus stone,
comes from Murcia, Spain. At Mount Apatite, Auburn, Maine, crystals
of pink, green, and violet colors have been obtained which sufficiently
resembled tourmaline to be mistaken for it.
Apatite occurs most commonly in metamorphic crystalline rocks,
especially limestone. It is also found in granites and mica schists,
and in sedimentary rocks ; but in the latter it is usually an amorphous
FLUORITE, OR FLUORSPAR
Few if any minerals exceed this in beauty and variety of colors. In
transparency and luster also it leaves little to be desired. Yet its soft-
ness and brittleness are such that it can have but a limited use for gem
purposes. In color it imitates closely many of the well-known gems, and
cut fluorites are often designated as "false" emerald, ruby, amethyst,
topaz, etc. From genuine stones of these names fluorite can readily be dis-
tinguished by its relative softness. Its hardness is 4 in the scale, and it is
therefore readily scratched by a knife-blade or a piece of glass. Fluorite
crystallizes in the isometric
system, and has an eminent
cleavage parallel to the faces
of the octahedron. This cleav-
age is so strongly developed
that it is difficult in cutting
the mineral to prevent cracks
starting and portions breaking
off. The cleavage also pro-
duces flaws in the stones.
Crystals of fluorite generally have the form of simple cubes. These
cubes are sometimes modified by other forms, and twinned cubes are
not uncommon. One of the most unique and pleasing properties of
fluorite is that known as fluorescence. When pieces of the mineral are
heated gently their interiors light up with a bright glow, usually colored,
and this color is quite independent of that of the mineral a blue fluorite,
for instance, often exhibiting an emerald-green fluorescence, a green
stone, a purple, and so on. Sometimes the heat of the hand, or the
striking of two pieces together, is sufficient to excite this glow, and an
increase of heat may cause it to change color. If heated too highly or
too long the mineral loses both this property and its inherent color. The
cause both of the color and the fluorescence is undoubtedly hydrocarbons
which exist in the mineral.
Fluorite is a simple fluoride of calcium, having the percentage com-
position fluorine 48.9, and calcium 51.1. It fuses rather easily before
the blowpipe to a white enamel, which gives an alkaline reaction. Its
Crystal forms of fluorite
specific gravity ranges from 3 to 3.25. Besides the transparent crystal-
lized forms, it is found in fibrous and granular masses. It is a common
mineral, and widely distributed. Its most common occurrence is in veins
accompanying ores of lead, silver, etc. It also forms beds. The locali-
ties affording the best known, and in many respects the finest, fluorite
are Cumberland and Derbyshire, England. In these localities the fluorite
is known by the name of Blue John, or Derbyshire spar, and is worked
to some extent into large ornamental objects, such as table-tops, vases,
etc. These articles are turned on lathes, the stone being first soaked in
gum-water, or similar adhesive, to prevent its falling apart. One of the
finest pieces of this sort of work ever executed is to be seen in the
Museum of Practical Geology, London. This object is a vase 2 feet
8 inches high, and 3 feet 7 inches in its greatest circumference. It was
made by Mr. Vallance, of Matlock, from several pieces of fluorite occur-
ring near Castleton, in Derbyshire.
The mining district of Saxony affords large quantities of fluorite.
Red is one of the rarest colors exhibited by this mineral, and red fluorite
comes almost exclusively from the St. Gothard, Switzerland.
In our own country many deposits of fluorite occur, though little use
is made of them for ornamental purposes. ^-Macomb, New York, has
furnished a large quantity of green crystals, exceeding in size and equal-
ing in color any ever found. An extensive deposit of fluorite in Illinois
is mined for use as a flux, but the crystals are rarely clear enough for
Hematite is an oxide of iron occurring in nature which takes on a
variety of forms and shades, but is used in jewelry only when compact
and of an iron-black color. In this form it is used especially for in-
taglios, but also for carving into ornaments of various sorts. Its hardness
is 6, and specific gravity 4.9-5.3. Its composition is, iron 70 per cent,
and oxygen 30 per cent. While in a mass it is invariably opaque, and
often black in color ; in a thin splinter it may be seen to be slightly trans-
lucent and red. This red color always characterizes the powder or streak
f hematite, and is one of the surest means of identifying the mineral.
'As the color resembles that of blood, the Greeks believed the mineral to
be concreted blood, and the name hematite is from their word for that
substance. Under the name of bloodstone it was long believed to be a
curative of hemorrhages, and Robert Boyle, the eminent physicist, writing
as late as 1672, gravely relates a cure of a case of nasal hemorrhage of
long standing through wearing a bloodstone about the size of a hen's
egg about the neck.
Powdered hematite forms the rouge of commerce used so extensively
Hematite was used in the carved form by the ancients as well as the
moderns, a number of cut pieces having been found in the ruins of Baby-
lon. Intaglios of it have also come down to us from the Romans. Large
polished surfaces of hematite make excellent. mirrors, and frequent use was
made of it for this purpose in earlier times. Hematite is so abundant
over the earth's surface that it has little intrinsic value except as an ore
of iron. That used in jewelry comes largely from northern Spain. Hem-
atite of a similar character is obtained in the Island of Elba, Cumberland,
England, and in the Lake Superior region of our own country. Besides
its use for seals, it is employed to make imitation black pearls. Certain
fibrous occurrences of hematite when cut in rounded forms give a star-
like appearance similar to that exhibited by star sapphires.
Pyrite, also known as marcasite by jewelers, is a brass-yellow min-
eral with metallic luster, employed to some extent for purposes of orna-
ment. It is widely distributed in the earth's crust, and from its yellow
color and metallic luster is often mistaken for gold. A common name
for it, therefore, is " fool's gold." In composition it is a sulphide of iron,
the percentages being, sulphur 53.4 and iron 46.6. Its hardness is a little
below that of quartz, or 6^. The name pyrite is from the Greek word
Crystal forms of pyrite
for fire, and was given in allusion to the fact that owing to its hard-
ness it will strike fire with steel. It is heavy, its specific gravity being
five times that of water. It is quite brittle. It crystallizes in the iso-
metric system, crystals of cubic or cuboidal forms being the most com-
mon. Owing to its abundance in nature it has practically 110 intrinsic
value except in large quantities, in which case it forms an ore of sulphur.
When cut into various objects of ornament, however, it has quite a
pleasing effect, and at times has been much in favor. It is used for
ornamenting bracelets, brooches, scarf-pins, and the like, and in certain
forms in rings.
For these purposes it has usually been artificially facetted, thus dis-
playing its brilliant luster. An American firm has recently, however,
employed the pyrite found in the form of a coating of small, bright
crystals, nearly uniform in height, for use in jewelry. These coatings
are obtained from beds of anthracite coal, and only require smoothing
on the back and cutting into pieces of suitable size and shape to be
One of the drawbacks to the use of pyrite in this way is its easy
liability to tarnish, and the difficulty afterwards of restoring the original
luster. Some groups of crystals will remain bright a long time while
others tarnish rapidly. This is especially true of marcasite, the ortho-
rhombic form of iron sulphide, which is sometimes confounded with
pyrite. This even decomposes and crumbles away in time.
Pyrite was used to quite an extent in earlier times for mirrors,
large pieces of it being ground and polished until they gave a good
polish. Among the remains of the Incas of Peru have been found
large numbers of these pyrite mirrors.
f This mineral, the name of which means " green-star stone," is solely
of American occurrence, and thus far has been found at but a single
locality. It occurs at Isle Royale, an island in Lake Superior, in the
form of beach pebbles. These pebbles come from the adjoining amygda-
loidal trap rock, out of which they weather. They are opaque, and
of light, bluish-green color, with a mottled effect arising from a stel-
lated or radiated structure. This structure, when the stone is polished,
affords a chatoyancy which is very pleasing. It is especially desirable
in a good stone that the radiation should emanate from the center,
in which case a cat's-eye effect is obtained. The pebbles which make
good stones are mostly small; but some an inch in diameter are
known. The hardness of the mineral is 5.5, and its specific gravity
3.18. It is not a homogeneous mineral but a mixture, composed
chiefly of a hydrous aluminum silicate. The stones have not attained
extensive use as yet, except as they are sold in quantities to tourists in
the Lake Superior region, i/
6/iAn occurrence of this mineral, which is used ornamentally to some
extent, is obtained, like chlorastrolite, in the form of waterworn pebbles
weathered out of an amygdaloidal trap. The pebbles are found on
the shores of Lake Superior, near Grand Marais. They are opaque,
and exhibit concentric structure in layers of various shades of color>
such as olive-green, flesh-red, cream, and white. There are often
several centers of structure in a single pebble, giving a unique and
pleasing effect. The pebbles range up to an inch in diameter, and
in cutting are simply rounded so as to best bring out the various
colors and centers of structure. The hardness of the mineral is 5;
specific gravity 2.2-2.4. Its luster is vitreous to pearly. Its compo-
sition is that of a hydrous silicate of aluminum, sodium and calcium,
and its occurrence is almost wholly as a secondary mineral filling the
cavities of igneous rocks.
The mineral at Grand Marais has long been known as thomsonite,
and is generally sold under that name; but Professor N. H.Winchell
affirms that it is in reality the allied mineral mesolite. ( i/
This mineral affords a semi-transparent stone, which, when of a deep
oil-green color, may have a limited use in jewelry. It does not often occur
in nature in the form of large distinct crystals, but usually as aggre-
gates of minute crystals, in firm incrusting masses, with a radiated
structure. Portions of these masses, when of a uniform color, form,
when cut en cabochon, pleasing stones.
In composition prehnite is a hydrous silicate of aluminum and cal-
cium, having the percentages : silica 43.7, alumina 24.8. It is easily
fusible before the blowpipe and is attacked by acids. Its hardness
is 6.65; specific gravity 2.80-2.95; its luster is vitreous. Its occur-
rence is almost wholly in connection with basic eruptive rocks, in the
veins and cavities of which it forms a secondary mineral.
Some of the most richly colored prehnite known is obtained at Pater-
son and Bergen Hill, New Jersey. In the Lake Superior region prehnite
accompanies native copper, and affords a stone which is considered
worthy of cutting. Many localities in the Alps furnish prehnite, and
handsome pieces are obtained by polishing masses occurring in'^China.
Some prehnite comes from the Cape of Good Hope, and when cut
is known as "Cape chrysolite."
Rhodonite is a silicate of manganese, of a pink, or flesh-red color.
It does not furnish transparent gems, but occurring massive in large
pieces affords material for table-tops, vases, jewel-boxes, paper-weights,
and other large objects in which such a color is desired. The stone
has a slight translucency, which heightens its effect when polished,
and it is also like jade in being quite tough. The Russians use it more
extensively perhaps than any other people, often introducing it into
ornamental and decorative works, and it is a stone especially prized
by the Imperial family. The hardness of rhodonite is 5.5-6.5 ; its spe-
cific gravity 3.4-3.7. Before the blowpipe it fuses easily and becomes
black. It crystallizes in the triclinic system. Its chemical composition
when pure is, silica 45.9, manganese protoxide 54.1. Rhodonite occurs
in a number of localities, the district of Ekaterinburg, in the Urals,
affording that used by the Russians. Here it occurs in a massive,
marble-like form. At^Cummington, Massachusetts, according to Kunz,
large quantities of a pink and red color occur which have been used
for ornamental objects. A feature of this rhodonite is its being mottled
and streaked with black, which causes it to blend prettily with silver.
Rhodonite of the variety of fowlerite, that is, containing zinc, occurs
among other zinc ores at Franklin, New Jersey. It is sometimes used
for ornamental purposes.
Satin Spar, polished (Italy).
Thulite, polished (Norway).
Serpentine, polished (Cornwall, England).
Smithsoiiite, polished (Greece).
Serpentine, polished Cornwall, England).
Serpentine, polished (Cornwall, England;.
Another rose-red massive stone is furnished by the variety of zoisite
known as thulite. This resembles rhodonite in color somewhat, but
is easily distinguished by its chemical characters, zoisite being a hydrous
silicate of calcium and aluminum. It is somewhat harder than rhodo-
nite, its hardness being 6-6.5. The name thulite is from Thule,
an ancient town of Norway, and the occurrence of thulite is confined
almost exclusively to that country. Its use for ornamental purposes
is very limited; but it answers well where objects of its particular
color are desired.
This mineral resembles jade in appearance and properties, and is
suited to many of the ornamental uses to which the former is put.
Not a little so-called jade is doubtless serpentine. The hardness of
serpentine is somewhat below that of jade, it being 5.5, and lower. It
is also lighter, its specific gravity being 2.50-2.65. The blowpipe and
chemical characters also distinguish it, serpentine being practically
infusible before the blowpipe, and decomposed by acids, while jade is
more or less fusible, and not attacked by acids. In composition serpen-
tine is a hydrous magnesium silicate having the percentages, silica 44.1,
magnesia 43.0, and water 12.9. Like jade it does not crystallize, but
occurs in massive forms, which show crystalline structure. One of the
most pleasing properties of serpentine is its luster, which is subresinous
to oily. This, coupled with translucency which characterizes most pre-
cious serpentine, and the excellent polish which it takes, make the stone
of rich effect.
The color of precious serpentine is primarily some shade of green, vary-
ing from yellowish-green to blackish-green. This color may be uniform
or mottled, or may include spots of other minerals, such as the white of
calcite, as in several of the serpentine marbles, or cherry-red from iron
oxide, as in the serpentine of Lizard, England. The name serpentine
alludes to the green, serpent-like cloudings best seen in serpentine marble.
Precious serpentine is obtained in many parts of the world, among
the localities being Afghanistan (which furnishes an almost transparent
variety in large masses), the Island of Corsica, Fahlun and Gulso in
Sweden, the Isle of Man, and the Lizard, Cornwall, England.
In the United States a rich green variety of serpentine, known as
williamsite, is found in Texas, Lancaster County, Pennsylvania, and is
cut into various charms and ornaments. It varies in color from dark
green to light apple-green. A golden to greenish - yellow serpentine
occurs at Montville, New Jersey, which would admit of use for the
manufacture of small objects, such as dishes and charms.
A variety of serpentine known as bowenite is found near Smithfield,
Rhode Island, varying in color from pure white to deep green.
<A dark green serpentine occurs at Santa Catalina Island, California,
which is of sufficient homogeneity to be turned into dishes of various
shapes, some being seven or eight inches in diameter.
Serpentine marble, which usually consists of a mixture of serpentine
and calcite, forms quite extensive deposits at several localities in the
country, among which may be mentioned Moriah, New York ; Dublin,
Harford County, Maryland ; National City, California ; and Valley,
Washington. This is used like marble as slabs for table-tops and wall
Coarse, common serpentine forms extensive rock masses, and moun-
tains of it exist ; but the use of the mineral for ornamental purposes is
confined to pieces of pleasing color, homogeneity, and translucency.
Malachite is a green carbonate of copper containing water, the per-
centages being in the typical mineral: cupric oxide 71.9, carbon dioxide
19.9, and water 8.2. It is the common form which copper assumes
when it, or even its ores, oxidize in the air. Many of the green stains
on rocks, or minerals, can be correctly referred to malachite. It is only
valued for ornamental purposes, however, when it occurs in compact
masses, usually exhibiting concentric layers. Malachite in this form
takes a fine polish. Malachite is not a hard mineral, its hardness being
between 3.5 and 4. It can, therefore, be scratched with a knife. It
is comparatively heavy, weighing four times as much as an equal
bulk of water. When heated before the blowpipe it fuses easily,
coloring the flame green. By heating long enough on charcoal it can
be made to yield a globule of copper. It is easily attacked by com-
mon acids, causing effervescence of carbon dioxide. This test can
be used to distinguish it from the silicate of copper, chryscolla, which
has the same color.
Besides its occurrence in massive forms, as noted above, malachite
not uncommonly is found in tufts and rosettes incrusting other min-
erals. This is an especially common occurrence in mines in Arizona,
and affords specimens of great beauty, especially when the green tufts
of malachite are seen upon brown limonite, for then the appearance
of moss on wood is closely simulated. Such material is, of course,
too fragile to be used for decorative purposes.
Malachite is prepared for ornamental use by sawing masses of the
character of those previously referred to into thin strips, which are
then fastened as a veneer on vessels of copper, slate, or other stone
previously turned to the desired shape. Putting pieces together so that
neither by their outlines nor color will it appear that they are patch-
work, requires a high degree of skill, and such work is done almost
exclusively in Russia. Table tops, vases, and various other vessels are
manufactured in this way, and form objects of great beauty. The pillars
of the Church of Isaac, in St. Petersburg, are of malachite prepared in
this way, and there are similar pillars in the Church of St. Sophia, Con-
stantinople, said to have been taken from the Temple of Diana at Ephesus.
Occasionally the desired object can be turned from a single piece
of malachite; but pieces of sufficient size for this purpose are rare.
Bauer describes one piece found in the Gumeschewsk mines which was
17^ feet long, 8 feet broad, and 3^ feet high, and compact throughout.
This is probably the largest single mass known.
Russia furnishes most of the malachite suitable for work of this
kind, and the art of cutting and fitting the stone is possessed almost
exclusively in that country. Most of the Russian malachite has been
obtained from the mines of Nizhni-Tagilsk and Bogoslowsk, in the
northern Urals, or Gumeschewsk, in the southern. The supply has
gradually decreased till now only the Nizhni-Tagilsk mines are pro-
ductive. The malachite occurs there in veins in limestone.
Besides the Urals, fine malachite, suitable for cutting, comes from
Australia. Burra Burra, in New South Wales, and Peak Downs, in
Queensland, are localities whence good Australian malachite is obtained.
Malachite, as a mineral, is common in copper mines in the United
States; but it is only in Arizona that it is found of a quality suitable
for cutting. A variety from Morenci, Arizona, consists of malachite
and azurite, and gives a combination of green and blue that is unique
and pleasing. Less use has been made of such material for ornamental
purposes than might have been, for most of it has unfortunately been
smelted as a copper ore.
Malachite is rarely used for rings, or small jewels, being cut most
extensively into earrings, bracelets, inkstands, and similar objects. Art
objects of malachite seem to have been in much favor with Russian em-
perors as gifts to contemporaneous sovereigns, and so bestowed are to be
seen in numerous palaces in Europe. Perhaps the most famous of these
gifts is the set of center-tables, mantelpieces, ewers, basins, and vases
presented by the Emperor Alexander to Napoleon, and still to be seen
in an apartment of the Grand Trianon at Versailles.
Malachite was well known to the ancients, and like other precious
stones was worn as an amulet. It was called pseudo - emerald by
Theophrastus. Its name is from the Greek malake, the word for
mallows, and was given doubtless on account of its green color.
It was regarded in the sixteenth century as a powerful anaesthetic,
being used internally or, applied to the injured parts. It was also used
as a purgative and to increase the strength and growth of children. The
Chinese still ascribe magical properties to vases made from it.
Azurite, the blue mineral which often accompanies malachite, is like-
wise a hydrous carbonate of copper, and occasionally occurs so that it
can be used with malachite for ornamental purposes.
This mineral in its pure state is too soft to be used as a gem,
but mixed with quartz, or constituting practically a stain, it affords
blue and green stones, resembling turquois on the one hand and chryso-
prase on the other. In fact, it is not unlikely that some of the so-called
turquois obtained in Utah and Nevada is in reality chrysocolla. Typically
chrysocolla is a hydrous silicate of copper, having the percentages : silica,
34.3, copper oxide, 45.2, and water, 20.5. It thus resembles dioptase
in composition, but unlike that mineral it does not crystallize. Its
hardness varies from 2 to that of quartz if mixed with that mineral.
Its specific gravity is slightly greater than that of quartz. Its blowpipe
reactions do not differ from those of turquois essentially, because of the
content of copper in the latter, but chrysocolla gives no test for phos-
When of good color and hardness chrysocolla affords a stone resem-
bling turquois or chrysoprase.
Chrysocolla occurring in Nizhni-Tagilsk, in the Urals, is of a sky-
blue color, and is known as demidovite. It has been cut to some extent.
In our own country chrysocolla occurs in numerous copper mines, espe-
cially in Michigan, Arizona, and Nevada, but not much use has yet been
made of it in jewelry.
The name chrysocolla is from the Greek, and means gold glue. It
was so called from its resemblance to a substance used by the ancients
for soldering gold. It is mentioned by Pliny, and was probably known
to the Romans, though not used for ornamental purposes.
The name of " copper emerald," by which this mineral is sometimes
known, well indicates both its composition and appearance. No other
mineral so closely imitates the emerald in color, although it differs in
being slightly darker and less transparent. It possesses also a distinct
rhombohedral cleavage, so prominent as to give the mineral its name,
from two Greek words dia, through, and optomai, to see, because the
cleavage can be seen on looking into a crystal. Dioptase is a hydrous
silicate of copper, having the percentage composition: silica 38.2, cupric
oxide 50.4, water 11.4. It crystallizes in the rhombohedral division
of the hexagonal system, forming short prismatic crystals resembling
superficially an isometric dodecahedron. Its chemical characters suffi-
ciently distinguish it from emerald, as it gives before the blowpipe the
green flame of copper, and gelatinizes with hydrochloric acid. Its chief
defect as a gem consists in its lack of hardness, which is only 5. It is
therefore rather easily scratched. Its specific gravity is somewhat high,
3.28-3.35. It has vitreous luster, and is brittle.
The best dioptase comes from the Kirghese Steppes of Siberia, where
it occurs on the hill Altyn Tube, occupying seams in a compact lime-
stone. The crystals here are so perfect that they can be worn uncut.
Small crystals and rolled pieces are found in auriferous sands in various
places in the Jeniseian Government in Russia, and fine crystals are
reported from the Mindouli mine in the French Congo State. It has
also been obtained at the copper mines of Clifton, Arizona, but the
crystals are small, and of little value for gem purposes.
This stone was the sapphire of the Greeks, Romans, and Hebrew
Scriptures. Pliny likened it to the blue sky adorned with stars. Large
quantities of worked pieces of it are found in early Egyptian tombs,
and the Chinese have long held it in high esteem. Marco Polo visited
Asiatic mines of the mineral in 1271 A. D., and these had doubtless
been worked for a long time previous. Besides its value as a stone, it
was in former times used as a blue pigment, giving the ultramarine-blue.
In modern times not only has the esteem in which the stone is held for
ornamental purposes declined, but the mineral can be artificially made
so as to give the desired blue color for paints, and thus the use of the
natural lapis lazuli has greatly diminished. It is still, however, carved
to make vases, small dishes, brooches, and ring stones, and is used to a
considerable extent for mosaic work. When, also, pieces of sufficient
size and of a uniform color can be found, large carved objects may be
made which command a high price.
The stone known as lapis lazuli as it occurs in nature is not a single
mineral but a mixture of several, among which are calcite, pyrite, and
pyroxene. From these, however, it is possible to separate a mineral of
uniform composition sometimes crystallized in dodecahedrons, which is
probably the essential ingredient of the stone. This mineral is known
as lazulite, and in composition is a silicate of soda and alumina, with a
small quantity of sodium sulphide. It is by making a substance of this
composition that the artificial ultramarine is produced. The artificial is
said to be as good as the natural for a pigment, and can be produced for
a three-hundredth part of the cost. The natural lapis lazuli has a hard-
ness of 5^ and a specific gravity about like that of quartz. It is quite
opaque. In color it is blue, varying from the prized ultramarine to paler,
and at times is of a greenish shade. It is said the pale colored portions
can be turned darker by heating to a red heat. When the variety from
Chile is heated in the dark it emits a phosphorescent green light. The
stone in nature is often flecked with white calcite. Portions so affected
are not considered as valuable as the uniform blue. Grains of pyrite
are also usually scattered through the stone, giving the " starry " effect
referred to by Pliny.
Lapis lazuli usually occurs in 'limestone, but in connection with gran-
ite, so that it seems to be a product of the eruption of the granite through
the limestone. The lapis lazuli of best quality comes from Asia, the
mines being at Badakschan, in the northeastern part of Afghanistan, on
the Oxus River. The mining is done by building great fires on the rocks
and throwing water on them to break them. The yield at present is
small, not over 1,500 pounds a year being obtained. The lapis lazuli
from these mines is distributed all over Asia, going chiefly to China and
Russia. The price realized is said to be from $50 to $75 per pound.
Lapis lazuli of poorer quality comes from a region at the western end of
Lake Baikal in Siberia. The only other important locality is in the Andes
Mountains of Chile near the boundary of the Argentine Republic. This
material is not much used at the present time, on account of its poor
quality, but it was employed by the Incas for decorative purposes. One
mass 24x12x8 inches, doubtless from this locality, was found in a Peru-
vian grave, and is one of the largest masses of lapis lazuli known.
The walls of a palace at Zarskoe-Selo, Russia, built by order of
Catherine II., are entirely lined with slabs of lapis lazuli and amber.
Pulverized, the stone was used as a tonic and purgative by the Greeks
and Romans, and as late as the sixteenth century was supposed to be a
cure for melancholy. The name lapis lazuli means blue stone. Arme-
nian stone is another term by which the stone is known in trade.
This mineral, named after James Smithson, who founded the Smith-
sonian Institution in Washington, is a carbonate of zinc used chiefly as
an ore of that metal. It is usually of a dull, earthy character and
poorly fitted for ornamental purposes. In some occurrences, however, it
exhibits pleasing colors and a translucency reminding one of onyx.
When so occurring it may be cut into ring stones, or even vases and
other dishes of considerable size and beauty. The smithsonite from
Laurium, Greece, is that perhaps most extensively used in this way, its
color usually being some shade of blue. From Siberia a beautiful bright
green smithsonite is obtained, the green color being due probably to a
little admixed copper, and from the zinc mines of Arkansas and Missouri
a bright yellow form is derived, known locally as "turkey fat ore."
The yellow color here is due to a little cadmium. All of these forms of
smithsonite exhibit when polished a rich luster and subtransparency which
are pleasing. The hardness of the mineral is somewhat deficient for
enduring wear, this being but 5. It is rather heavy, its specific gravity
being 4.3 to 4.4. It is infusible, but soluble in hydrochloric acid with
effervescence. When heated before the blowpipe a coating is formed,
which is yellow when hot and white on cooling. These tests serve to
distinguish the mineral from any others with which it might be
The term alabaster is derived from a kind of ointment vases called
alabastra, which the Egyptians and peoples of a later period were accus-
tomed to carve out of stone. This stone was largely a stalagmitic calcite
obtained at Thebes, but it is probable that gypsum was also used to some
extent. At the present time the term is used loosely for either of these
minerals when employed for the manufacture of ornamental objects,
although stalagmitic calcite is now more generally designated as onyx.
Both calcite and gypsum are soft minerals, the hardness of the
former being 3, and that of the latter 2. They are not therefore fitted
to endure wear, and can only be employed for objects such as vases,
boxes, statuary, etc., not likely to be subjected to much attrition. Both
stalagmitic calcite, however, and gypsum take an excellent polish, and
preserve it if properly cared for.
The term alabaster when referred to gypsum is limited to the fine-
grained granular variety usually white or delicately shaded. It is
obtained largely at Castelino, near Leghorn, in Italy, and is used for
carvings of various sorts. Objects are often sold under the names of
alabaster that have been made out of plaster of paris by molding. These
can be distinguished from true alabaster by their lack of translucency.
Another form of gypsum used for ornamental purposes is that known
as satin spar. This is white, with a delicately fibrous structure, and
exhibits when polished a beautiful silky luster and pearly opalescence.
Large quantities of this cut in the form of necklaces, charms, etc., are
often sold at Niagara Falls and vicinity to tourists as made from material
found at the Falls. Although gypsum occurs there, it is not in this form,
and the material used in this way is really obtained in Wales.
Objects made from calcite can usually be detected by their softness,
as they scratch easily and deeply with a knife, and by their effervescing
when touched with a drop of any common acid. In the form of Mexican
onyx calcite is extensively used for ornamental purposes, and many
locally fashioned stones, such as the Petoskey, Michigan, fossil corals
(often called agates), and the Gibraltar stone, of Gibraltar, belong to this
r + +F
AMB.EK, MALACHITE, LA-flS-LAZULI AND AZURITE.
Lapis-lazuli, polished (Siberia).
Malachite and Azurite, polished (Arizona;.
IMahichite, polished (Australia).
Amber, polished, showing insects enclosed (Coast of Baltic Sea).
Amber, rolled pebble (Coast of Baltic Sea).
Malachite, polished (Ural Mountains).
Few minerals have been longer in favor for ornamental purposes
than amber. Among remains of the earliest peoples, such as the
Egyptians and cave-dwellers of Switzerland, it is found in carved
masses, indicating that it was highly prized. The Phoenicians are
said to have sailed to the Baltic for the purpose of procuring it,
while the Greeks' knowledge of it is indelibly preserved in our word
electricity, derived from their word electron.
Amber is a fossil gum of trees of the genus Pinus, and is thus
a vegetable rather than mineral product. In color it is yellow, varying
to reddish, brownish, and whitish. Its hardness is 2 to 2.5, it being
slightly harder than gypsum and softer than calcite. It cannot be
scratched by the finger nail, but easily and deeply with a knife. It
is also brittle. Its specific gravity is scarcely greater than that of water,
the exact specific weight being 1.05-1.096. It thus almost floats in
water, especially sea water. It is transparent to translucent. On being
heated it becomes soft at 150 C., and at 250 to 300 melts. It
also burns readily and at a low temperature, a fact which has
given rise to the name of bernstein, by which the Germans know
it, and to' one of the Roman names for it, lapis ardens. Rubbed with
a cloth it becomes strongly electric, attracting bits of paper, etc. As
already noted, our word electricity comes from the Greek for amber,
this seeming to be one of the first minerals in which this property
was noted. Amber, being a poor conductor of heat, feels warm rather
than cold in the hand, contrary to most minerals. It is attacked but
slowly by alcohol, ether, and similar solvents, a property by which
it may be distinguished from most modern gums and some other fossil
ones. In composition it is an oxygenated hydrocarbon, the percentages
of these elements being in an average sample: carbon, 78.94, hydro-
gen, 10.53, and oxygen, 10.53. The mineralogical name of amber
is succinite, a word derived from the Latin succum, juice. One of its
constituents is the organic acid called succinic acid.
The present source of most of the amber of commerce is the Prussian
coast of the Baltic Sea, between Memel and Dantzig, although it is
found as far west as Schleswig-Holstein and the Frisian Islands, and
even occasionally on the shores of Denmark, Norway, and Sweden.
From time immemorial pieces of amber have been cast upon the shore
in these localities, and their collection and sale has afforded a livelihood
to coast-dwellers. Such amber is called sea stone, or sea amber, and
is superior to that obtained by mining, since it is usually of uniform
quality, and not discolored and altered on the surface. Owing to its
lightness, the amber is often found entangled in seaweed, and the
collectors are accustomed to draw in masses of seaweed and search
them for amber. Amber so obtained is called scoopstone, nets being
sometimes used to gather in the seaweed. In the marshy regions men
on horseback, called amber riders, follow the outgoing tide and search
for the yellow gum. It is also searched for by divers to some extent.
From the earliest times the title to this amber has vested in the State,
and its collecting has been done either under State control, or as at
present, when a tax is levied by the government upon it. This tax
is levied on the amber that is mined, as well as that obtained from
the sea, and brings a revenue at the present time of about $200,000.
Up to 1860 the methods of procuring amber were largely confined
to obtaining it in the manner above noted. As it was evident, however,
that the sea amber came from strata underneath, and that if either
by dredging or mining these strata could be reached a much larger
supply .could be obtained, exploration was carried on by mining methods
with successful results, and the principal amount of the amber of com-
merce is now so obtained. The strata, as shown in the mines of Sammland,
the rectangular peninsula of East Prussia, where most of the mining
is carried on, are : First, a bed of sand ; below this a layer of lignite
with sand and clay; and following this a stratum of green sand,
fifty or sixty feet in thickness. While all these strata contain scattered
pieces of amber, it is at the bottom of the green sand layer that the
amber chiefly occurs, in a stratum four or five feet thick, and of very
dark color. It is called the " blue earth." This stratum is of Tertiary
age, and there can be no doubt that its amber represents gum fallen
from pines, which grew at this period, and whose woody remains are
represented to some extent in the layer of lignite. It is probably true,
as Zaddach remarks, that the amber has been collected here from older
deposits. One of the most interesting proofs of the vegetable origin
of amber is the occurrence in it of insects, sometimes with a leg or wing
separated a little distance from the body, showing that it had struggled
to escape. These insects include spiders, flies, ants, and beetles, and
even the feather of a bird has been found thus preserved. Indeed,
the amber deposits have furnished important contributions to our knowl-
edge of Tertiary life. Inasmuch as the pieces bearing such remains are
valued more highly than ordinary amber, unscrupulous persons have
at times found profitable employment in boring cavities into pieces
of amber, introducing flies or lizards into them, and then filling up
the hole with some modern gum of the same color. It is said that
all amphibious or water animals seen in amber have been introduced
in this way.
Besides the counterfeiting of the inclusions of amber there are several
substitutes for the gum itself. These are chiefly celluloid and glass,
the substitution of the former being dangerous if used for the embel-
lishment of pipes, on account of its inflammatory character. Celluloid
can be distinguished from amber by the fact that when rubbed it
does not become electric, and gives off an odor of camphor instead
of the somewhat aromatic one of amber. It is also quickly attacked
by alcohol, or ether, and when scraped with a knife gives a shaving
rather than a powder, as amber does. Glass can be distinguished by
its cold feeling and greater hardness and specific gravity.
Besides these substitutes, it has been found possible by heating and
pressing the scraps of amber not large enough for carving, to make
them into a homogeneous mass, which is sometimes sold as amber
and sometimes as amberoid. Amber is worked to desired shapes by
turning it on lathes, or by cutting by hand. By heating it in linseed
oil it becomes soft, so that it can be bent, and often all opaque spots
can be made to disappear by such treatment. The amber which is
most highly prized of any in the world comes from Sicily. Eight hun-
dred dollars have been paid for pieces of this no larger than walnuts,
making their value approach that of diamonds. The beauty of the
Sicilian amber consists in the variety of colors which it displays,
blood -red and chrysolite -green being not uncommon; and in the fact
that these often exhibit a fluorescence, glowing within with a light
of different color from the exterior. Chemically the Sicilian amber
is not the same as the Prussian, as it contains less succinic acid,
and is somewhat more soluble. In other respects it is not essen-
tially different. It occurs chiefly on the eastern and southeastern coasts
of the island, being washed up in a manner very similar to the Prus-
Amber has been found in several places in the United States, but
there is little of commercial value. It is mostly connected with the
Cretaceous glauconitic, or green sand deposits of New Jersey, fragments
being frequently found there. This amber is of yellow color, but not
so compact or lustrous as foreign amber. Amber has also been reported
from the marls of North Carolina, some of the coal-beds of Wyoming,
and in connection with lignite in Alaska. In the latter region the
natives are said to carve it into rude beads.
Amber occurs in small quantities in several countries of Europe,
such as near Basel, in Switzerland; near Paris, in France; and near
London, in England. It is also found in many parts of Asia, these
localities being a source of supply to the Asiatic countries, such as
China and India. Occasionally amber is obtained from Mexico which
has the beautiful fluorescence of the Sicilian article, though the exact
locality whence it comes is not known. Specimens of carved amber
are found among the relics of the Aztecs, and it is probable that they
used it for incense. The early use of amber by European peoples has
already been referred to. There are references to it in the most ancient
literature, and worked masses of it are found among human relics
of the greatest antiquity. Up to comparatively modern times it was
an important article of commerce among widely scattered peoples, and
had much to do with bringing about communication between them.
Together with tin it was one of the chief objects which led the Romans
to penetrate the Gallic regions to the west and north of the Mediter-
ranean, and Pliny says that " it had been so highly valued as an
object of luxury that a very diminutive human effigy made of amber
had been known to sell at a higher price than living men, even in
stout and vigorous health." One of the most elaborate of the Greek
myths is that which accounts for the origin of amber. It runs in
this wise: Phaethon, undertaking to drive the chariot of his sun-god
father, Helios, lost control of his steeds, and approaching too near
the earth set it on fire. Jupiter to stop him launched a thunder-bolt
at Phaethon, and he fell dead into the Eridanus. His sisters lamenting
his death were changed into poplars, and their tears became amber.
According to another legend amber is the tears of the birds Meleagridae
who weep for their brother Meleager. Moore refers to this legend in
"Around thee shall glisten the loveliest amber
That ever the sorrowing sea-bird hath wept."
In the Odyssey one of Penelope's admirers gives her an amber
necklace, and Martial compares the fragrance of amber to the fragrance
of a kiss. Milton writes of amber, and Shakespeare mentions it both
in "Love's Labor Lost" and "The Taming of the Shrew."
Necklaces of amber are popular wedding presents among the peasants
The properties assigned to amber, both as a charm and as a medicine,
have been many. From the earliest times it has been used as an amulet,
being supposed to bring good luck and to protect the wearer against
the evil eye of an enemy. Necklaces of amber beads are used to this
day as preventive, or curative, of sore throat, and the Shah of Persia
wears around his neck a cube of amber reported to have fallen from
heaven in the time of Mohammed, which is supposed to have the
power of rendering its wearer invulnerable. Amber was also taken
internally in former times as a cure for asthma, dropsy, toothache,
and other diseases, and to this day is prescribed by physicians in
France, Germany, and Italy for different ailments.
The use of amber for artistic and decorative purposes has declined
considerably since the Middle Ages ; but magnificent illustrations of its
employment for these purposes are to be seen in many European
museums, notably the Green Vaults of Dresden.
In this country a beautiful collection of objects made of amber is to
be seen in the Boston Museum of Fine Arts.
Though so soft and easily destructible a substance amber endures with
ordinary care as well as the hardest stone, and many works of art
formed from it are well preserved.
Jet is a variety of coal which, being compact, takes a good polish, and
hence can be used in jewelry. Its hardness is between 3 and 4, and
specific gravity 1.35. It is a kind of brown coal or lignite, and retain-
ing as it does some of the original structure of the wood, is not brittle
and smutty as is most coal. To be of the quality desirable for cutting
it must be black, of a uniform color, and have a somewhat fatty luster.
The jet of commerce has for a long time come chiefly from Whitby,
Yorkshire, England. It occurs here as layers in schists of Upper Lias
age. The industry of mining and cutting the jet has at times reached
extensive proportions. In 1855 twelve hundred to fifteen hundred arti-
sans were employed in the work, and the annual value of the output was
$100,000. While Whitby is still the center of the industry, the demand
for jet has considerably decreased, and the trade has suffered a serious
setback. The jet manufactured in England is not all of local origin,
much of it being obtained from France, Spain, Italy, Wurtemberg, and
the Orient. Near the close of the eighteenth century considerable cut-
ting of both foreign and domestic jet was carried on in France, but the
industry is now largely abandoned. Good jet occurs in numerous locali-
ties in America, especially in Colorado, and in Pictou, Nova Scotia, but it
cannot be cut profitably to compete with the English product. In the
anthracite coal regions of Pennsylvania this variety of coal is cut into a
great variety of objects, which find a more or less extensive sale. Jet is
employed chiefly for mourning jewelry. The decline in its use has come
partly from a loss of its popularity and partly from the substitution for it
of black onyx or black glass. These latter can be prepared somewhat
more cheaply than jet, and while sometimes fraudulently substituted for
that mineral, are often preferred when an opportunity for a choice is
given. If it is desired to distinguish jet from either of these, it can be
known by being softer and lighter, and by having a warmer feeling in
the hand. Hard rubber and celluloid are also sometimes substituted for
jet, in which case they can be distinguished by the fact that jet does not
give a shaving under the knife, but crumbles away. The manufactured
articles are usually also given their form by being pressed in molds, and
by close inspection traces of the molds can be seen.
Jet seems to have been known to the Romans, their word for it
being " gagat," of which jet is probably a corruption. The Greeks also
prized the mineral, and considered it when powdered and mixed with
wine a preventive of toothache. When mixed with beeswax they
believed it to be a remedy for tumors, and burned as an incense it was
supposed to drive away devils.
Relics of the early Saxons also disclose numbers of jet ornaments,
which show that it was in use among them.
Jet is sometimes known as " black amber," a name not inappropriate
when the similarity in origin of the two minerals is considered.
Pearl is not a mineral in the strict sense of the word, but has long
been associated with gems in thought and use.
Like amber, jet, and coral, pearls are a product of organic or living
forces, not of inorganic nature. Mollusks, chiefly of the order of bivalves,
are the organisms which produce pearls. They are a product, however,
not of health and normal life, but of disease and abnormal conditions.
This is well known by the pearl-fishers, so that, in searching for pearls,
they pass by the young, well -formed mollusks, to gather only those
appearing old, diseased, and distorted. The formation of pearls by a
mollusk is generally believed to be the result of some persistent irrita-
tion of the mantle. The agent of irritation has been thought to be a
grain of sand, a bit of seaweed, an infusorian, a parasite, or an egg of the
mollusk itself. The origin of the pearl has been supposed to be due to
an effort on the part of the mollusk to protect itself from such an irri-
tant as one of those above mentioned by secreting over it a calcareous
deposit similar to that of which it forms its shell.
Some recent investigations by Dr. H. L. Jameson of London go to
show that many free pearls originate through the entry of a trematode
worm into the epithelium of the mantle of a pearl-bearing mussel. The
mussel, in order to protect itself against the parasite, deposits pearly
matter around it. Even if the parasite leaves the mantle the formation
of the pearl will continue. The life history of this parasite is interesting
in that at different times it lives in three hosts. The first, in the region
where Dr. Jameson studied it, is a so-called "tapestry shell," the second
the pearl mussel, and the third two members of the duck family. The
eggs of the parasite passing out with the faeces of the duck enter the
body of the tapestry shell, then pass to the mussel, and when the latter
is eaten by the duck, reach the intestine of the latter. This knowledge
makes it seem likely that it will be possible ere long to infect pearl-
bearing mollusks with the parasite in large quantities, and hence to
greatly increase the production of pearls.
The deposit of pearl has the color and character of the interior of
the shell, or if the color of the shell varies in different portions, that of
the part of the shell which is nearest. Unless the interior of the shell
possesses the peculiar nacreous luster desired in pearls, these will be
of no value.
The form and size of the pearls produced by mollusks varies con-
siderably. Only those which are perfectly spherical or drop-shaped are
considered of first quality for jewelry, but these are only a small part of
the forms produced. Irregular protuberances or convexities often distort
the spherical form, and highly complex and grotesque shapes occur. One
such pearl is known having a remarkable resemblance to a bust of
Michael Angelo. Others resemble insects or fruits. These resemblances
can be enhanced by proper mounting and the addition of a little gold
and enamel. Some fanciful work of this kind has been done, and a large
collection of such pearls is preserved in the Green Vaults in Dresden.
Such pearls are known as baroques, and formerly had comparatively
little value, but at
the present time they
are being employed
in the most costly
jewelry. Not infre-
quently the pearl be-
comes attached to
the interior of the
shell, as is the one
shown in the
colored plate. Such
pearls can be used by
cutting them away
from the shell, but
they have much less value than those well formed on all sides. Loose
pearls which form flat on one side are called button pearls, and are worth
only about twenty-five per cent less than round pearls. Again, pearls may
be hollow. Such are called coque de perle, and have little value if their hol-
low nature be known. This, however, is not always the case, as is shown by
an instance mentioned by Kunz, of a New York lady who had purchased
a pearl apparently of good quality, except for a little black spot on one
side. This was mounted and worn as an article of jewelry until, while
its owner was applauding at the opera one evening, the pearl broke and
disclosed its interior filled with a white, greasy clay.
The Chinese take advantage of the habit of mollusks to cover any
intruded substance with pearl, to introduce into the shells of these
animals, under the mantle, beads and small images. The mollusk is
returned to the water, and in about a year's time taken out again, when
Shell showing images of Buddha inserted during the life of
a mollusk and then covered with a pearly deposit. After Kunz
the objects are found to be coated with a pearly substance. Pearls so
formed, however, are comparatively dark and lusterless, and have by
no means the value of those of wholly natural origin.
Pearls vary in size from those of microscopic dimensions to those as
large as a pigeon's egg. The latter are, of course, very rare.
The Shah of Persia is said to possess the largest pearl known, it
being about one and one-third inches in length in one direction and one
inch in another. A pearl in the Austrian crown weighs 300 carats, and
one in the South Kensington Museum weighs 455 carats. The small
pearls used in jewelry are known as seed, dust, or sand pearls.
Pearls are chiefly white in color, but many are tinted yellow or pink;
some are gray, green, or purple, and many other colors occur. Black
pearls are obtained in certain fisheries. The pearls from the Unios of
North America are of almost every shade.
Pearls of pure white color, if of the proper luster, are those most
highly prized in Europe and America, although a slight pinkish tinge
does not injure the value. They must, however, have the transparency
of the true pearl and not be " chalky." In China and India pearls of
yellow color are preferred.
The hardness of pearl is 4, and its specific gravity 2.65-2.68. It is
thus like that of shell or " mother of pearl," which might be expected
from the fact that both are of the same chemical composition carbonate
of lime. Owing to their low hardness pearls are easily scratched, and on
account of their composition are attacked by acids. They thus deterio-
rate with age, losing their polish and luster and often becoming black and
unsightly. No way of positively restoring the luster of pearls is known,
although occasionally the outer marred coating can be removed by those
skilled in the art, and a lustrous surface be found beneath.
The Ceylonese are accustomed to feed pearls which have become dull
to chickens. After the pearl has remained in the crop of the bird a few
hours the fowl is killed and the pearl removed. The movement and
friction to which the pearl has been subjected in the bird's crop are
usually found to have restored its luster to some extent.
To preserve pearls as long as possible they should be wiped with a
clean linen cloth each time after being worn, and be kept in a dust-tight
box carefully wrapped in linen. Hot or boiling water injures and in
time destroys their luster, and many valuable pearls have been ruined
because the mollusk which contained them was boiled before opening.
The mollusks which yield pearls are many, and pearl-fishing is an
industry carried on in many parts of the globe.
The pearl mollusk or pearl oyster, par excellence, is that known by
the scientific name of Meleagrina (Avicula) margaritifera. This mollusk
has a bivalve shell averaging seven or eight inches in diameter, and gen-
erally thick. The exterior is of a greenish-black color, while the interior
is silver -white with pearly luster. The latter forms indeed the well-
known "mother of pearl." This mollusk inhabits warm seas, occurring
especially in sheltered localities in the Indian Ocean, and occasionally
throughout the tropical zone of the Pacific Ocean. It groups itself in
colonies like the common oyster, usually on coral banks at a depth of
twenty to thirty feet. It is not free moving, but attached by a byssus,
which must be severed before the mollusk can be brought to the surface.
The pearl fisheries of the Indian Ocean chiefly center in the Straits of
Manaar between India and Ceylon. The fishing is largely confined to the
months of March and April, as the sea favors best at that time, and at
that season from fifteen thousand to twenty thousand fishers and dealers
are said to gather along the pearl coasts. The oysters are obtained by
divers, who go out in boats and secure the shells by diving. They
usually dive without appliances, and work under the water simply by
holding their breath for the time. Some fishers, however, make use of
diving suits and bells. The work is dangerous, not only on account of
the bodily strain, but because sharks prey upon the divers. The oysters
are unloaded from the boats into pits on the shore, where they are left
to putrefy, and the pearls are then washed out.
Other localities in the Orient where the pearl oyster occurs, and
where pearl-fishing is carried on in the same manner as above described,
are the Persian Gulf, the Red Sea, and the Sulu Archipelago. The Red
Sea fisheries furnished in earlier times an extensive supply of pearls, and
were probably the source of those used by the Romans. They are now,
however, largely exhausted. The Persian Gulf pearls are inferior in color
to those of Ceylon, and are known as "Bombay" pearls. The Ceylon
fisheries are under control of the colonial government, and are carefully
guarded to prevent exhaustion of the supply. The localities where the
fishers are to work are staked off, and when an area has once been
worked over it is allowed to lie "'fallow" for seven years, so as to allow
a new crop to grow.
So far as the American continent is concerned, the true pearl oyster
is found chiefly in the Gulf of California. It occurs here both on the
east and west coast, and as far south on the Pacific coast as the northern
boundary of Guatemala. It is also found on the Brazilian coast and
the western shores of South America.
The California pearl fisheries were in operation at the time of the
invasion by Cortez, and he sent a number of fine pearls which he
obtained there to the queen of Spain. Since that time the fisheries
have been carried on with a varying degree of persistence from time
to time, the beds having occasionally become practically sxhausted
through too reckless dredging. The right to work the beds is held
by the Mexican government, and the fisheries are leased by it to differ-
ent companies. Both the shells and the pearls are of value, the sales
of the one reaching as high a figure as of the other. Black pearls
are the specialty of these fisheries, and some of the finest known
have been found here. The total annual product from the fisheries
reaches at the present time a value of half a million dollars a year.
American pearls are known in trade as "Panama" pearls, and bring
a somewhat lower price than those of the Orient.
Besides the pearl oyster of the sea, a number of mussels which
make their home in the beds of fresh-water streams or lakes produce
fine pearls. These mollusks belong chiefly to the family Uwonida,
and include many species. They are bivalves, and live both in the
beds of running streams and in still bodies of water on muddy bottoms.
They are usually to be found at a depth below the surface of the water
of from two to twenty feet. They lie either on the surface of the
mud, or partly imbedded in it, and with their valves slightly open,
to allow access of water containing oxygen and food. At the slightest
touch the valves close, and remain so until danger is past. The lumber-
men of Canada take advantage of this peculiarity to collect the mollusks
for food by tying bushes on the rear of their rafts as they float down
stream, to which the clams attach themselves in considerable num-
bers. A somewhat similar method is pursued by the fishermen of the
Mississippi Valley, who collect the clams in great numbers for the
manufacture of pearl buttons. They row about with long iron rods
fastened across their boats, from which at intervals series of hooks
and chains dangle in the water, and to these the mollusks attach
themselves. The mollusks are removed from their shells by boiling,
hence any pearls which they might contain are rendered worthless.
The same method of fishing might, however, be used to gather shells
for pearls. Other methods used to gather the mollusks to search for
pearls are: raking the bottom with an iron rake; wading with naked
feet, and picking up any projecting shell as it is felt; or systematic
dredging. The use of a water telescope is said to facilitate the work
of individual search for mollusks likely to contain pearls. It consists
simply of a long, light, wooden box, one end of which is strapped
to the face, while the other, covered with glass, is immersed in the
water. Provided with this appliance the bottom of a river or lake can
be searched carefully. Enormous quantities of the Unios are destroyed
in the search for pearls, and the supply has become considerably
diminished in consequence. This waste might be avoided if care was
used in opening the shell not to injure the animal. This work is per-
formed in Germany by a thin blade of steel about an inch in width,
and bent at a right angle about an inch from the end. The thin
blade is inserted between the valves, and then turned at right angles
so that the shell is opened the width of the blade. The operator can
then feel about for pearls, and if none are found return the mollusk
to the water without having injured it. The search for pearls in this
country is usually carried on by persons out of regular employment,
and has rarely been reduced to a systematic occupation. The total
value of the pearls which have been obtained, however, is great, and
their price is steadily increasing. One of the first valuable pearls found
in this country was obtained near Paterson, New Jersey, in 1857. This
pearl brought at its first sale $2,500, and is to-day worth $10,000.
A sky-blue pearl weighing ninety-three grains, found at Caney Fork,
Tennessee, in 1897, was sold in London for $3,300. Pearls valued
at from $100 to $1,000 are frequently found in the waters of the
interior States, such as Wisconsin, Minnesota, and Arkansas. In Arkansas
large numbers of valuable pearls have been found loose in the streams,
so that many of the pearl-hunters are of the opinion that the mollusks
" shed " their pearls at intervals. While the region of the Mississippi
Valley is that in which the pearl -bearing mollusks chiefly abound,
they occur also in the waters of the Eastern States, and these furnish
an appreciable supply.
The common oysters and clams of the temperate sea coasts pro-
duce pearls no less than those of fresh waters; but they lack the
desired luster and transparency, and are considered of no value. Some
gastropod, or univalve mollusks, also produce pearls, among which
may be mentioned the Strombus of the West Indies and the Turritella
of the East Indies. These pearls are of rose tint, but are liable to fade,
and lack also the transparency of the true pearl.
Pearls seem to have been valued by peoples of all times, both civilized
and uncivilized. The Hebrew Scriptures make frequent references to
them, and there are many incidents in history showing the esteem
in which they were held by the Greeks and Romans. The best known
of these is probably Cleopatra's wager with Antony, that at a single
meal she would swallow the value of a whole province. In pursuance
of this boast she is said to have dissolved a pearl of great value in
a glass of sour wine, and then to have drank the wine. It may be
worth noting that this story cannot be literally true, since a pearl
of the size reported would only slightly dissolve in such a mixture.
If ground to a fine powder, however, the pearl might be swallowed
in the wine without injury to the system, and if this was done the
story can be credited. According to Pliny the wealthy Romans were
accustomed to mix pearls with their wine, presumably in this way,
to improve the flavor of the beverage. The name for the pearl among
the Romans and Greeks was Margarita, and the finest pearls are still
known by this term.
The Romans believed that pearls were solidified drops of dew,
which had fallen into the gaping shells of oysters. The size and
quality of the pearl were supposed to depend on the size of the dewdrop
and the purity of the air. Ancient Hindoo authorities describe pearls as
originating in elephants, clouds, boars, fishes, frogs, and oysters, the latter
being the most productive. In their view the effect of the pearl upon its
wearer varied with its color. A light yellow pearl brought wealth, one
more deeply colored, understanding, a white pearl, fame, and a blue one,
Among the Chinese and Hindoos to this day pearls are regarded as
of great medicinal value, and a large proportion of the imperfect pearls
obtained in the fisheries are used for this purpose. They are considered
beneficial in syncope, hemorrhage, and stomach troubles, and seed pearls
are mixed with sweetened water for use as a stimulant. Among the
Arabians and Persians pearls are used as a cure for insanity and all
mental diseases; for diseases of the heart, stomach, and bowels; and for
bleeding and skin diseases. A similar belief in the efficacy of pearls for
the cure of insanity existed in Europe as late as the seventeenth century.
The insane King of Spain, Charles, was given pearl powder mixed
with distilled water as a remedy. The Aztecs and Incas of America,
when first visited by the Spaniards, possessed quantities of pearls of the
finest luster and color. Large numbers of pearls are found in the
prehistoric mounds of America also, showing that even these people
held them in esteem. These pearls generally lack the luster of the
pearl of the present day ; but whether this has been lost through lapse
of time, or whether the Mound Builders were content with pearls that
would to modern people seem valueless, is not known. The mound
pearls are frequently found bored and strung.
The passion for pearls for ornament continues at the present day,
and they often command even higher prices than the diamond, weight
for weight. The price, however, depends so much upon individual
quality that no fixed scale of values can be given.
Emanuel gives the following qualifications, as necessary to a per-
fect pearl: " .
1. It must be perfectly round, or drop-shaped, seeming as if fashioned
or turned into shape.
2. It must have a perfectly pure white color.
3. It must be slightly transparent.
4. It must be free from specks, spots, or blemish.
5. It must possess the peculiar luster characteristic of the gem.
Pearls are sold by their weight in
grains, rather than by carats, four grains
equaling a carat. Seed pearls weighing
one grain are usually worth from one to
three dollars each. With the increase
in size, however, the increase in price is
rapid, a two-grain pearl being worth, for
instance, four times as much as a one-
grain pearl, a three-grain pearl nine ^*^ "
times as much, and so on. The largest
pearls bring, like the largest diamonds,
individual prices. The pearl is, per- ^^ ^^
haps, the only gem that does not need ^P ^BF
to have its beauties enhanced by cutting, ^^_ ^^_
nor can any polishing process improve ^J
its surface. The favorite use of pearls ^^
20 ^A 22
is to string them in necklaces ; but they ^^v
are also often set around other stones ^^^
to heighten their effect, or they are used 2B W
alone in rings.
There are numerous ways of pro- Bx ct sizes^of^earjsfrom 2 to 30
ducing imitation pearls, one of which,
invented many years ago by a French bead-maker named Jacquin, gives
remarkably accurate reproductions. The Jacquin pearls are made from
an easily fusible bluish glass, which is first drawn into tubes, and from
these, hollow globules of the desired size are blown. These are covered
on the inside with a solution of isinglass, and a substance called essence
of pearl, which is blown in warm, and spread over the interior by
rapid motion. When dry, the globules are filled with wax. The essence
of pearl, which constitutes the important feature of Jacquin's process,
consists of a silvery substance found beneath the scales of the fish
known as the bleak (Cyprinus alburnus). It is in the form of thin,
irregular rhombic plates, and is obtained by washing the scales, one
pound of essence being derived from seven pounds of scales. From
eighteen thousand to twenty thousand fish are required to produce
the latter amount of scales. The substance is, therefore, costly; and
owing to this fact, and the amount of labor and skill required to make
the pearls, they bring a considerable price. They can be distinguished
from genuine pearls by their greater hardness, and a colder feeling
in the hand. The holes in the false pearls, moreover, are comparatively
large, and have a blunt edge, while those made in real pearls are small,
and have a sharp edge. False pearls are sometimes made by turning
pieces of mother-of-pearl into a spherical form; but they are clumsy
imitations, and can be at once detected by the difference of luster
as a whole, and the variations of luster on different surfaces. A very
good imitation of black pearls is made by cutting pieces of hematite
into a spherical form. These counterfeit the luster of the black pearl
in a remarkable degree; but can be distinguished by their greater
weight and hardness.
Dredging Precious Coral
Of the great number of forms and species of coral known a single
one furnishes nearly all that is used in jewelry. This species is known
by the scientific name of Corallium rubrum, and belongs to the family
Gorgonidae of the group Alcyonaria. It is a branching coral, shrub-like
in its appearance, and grows to a height of a foot or more, with stems
an inch in diameter. If the living coral be examined it will be found
to consist of an outer fleshy or gelatinous portion inclosing an inner,
hard, calcareous skeleton. The outer portion is made up of numbers of
polyps, as the little coral animals are called, joined together. The pro-
jecting polyps look in life like little warts over the surface. Each has
eight tentacles. The internal skeleton differs from that of the majority
of corals in being red in color. When the coral animals die this internal
skeleton is left, and by polishing it the coral of jewelry is obtained. This
kind of coral grows almost exclusively in the Mediterranean Sea. The
localities where it is most abundant are the coasts of Algiers and Tunis,
the western coasts of Sardinia and Corsica, portions of the coast of
Sicily, the western coast of Italy, and a few localities on the southern
coasts of France and Spain. The coral forms banks at depths of from
ninety to one hundred feet, growing up from the bottom. That of the
greater depths has not as rich color as that nearer the surface, and does
not grow to so large a size. The work of dredging the coral is per-
formed by fleets of small vessels manned by crews of from six to twelve
persons. Work is carried on only in the summer months because of the
stormy weather at other seasons. The vessels are obliged to put out
about six miles to sea in order to reach the best fishing-grounds, and the
work is of a laborious and dangerous sort. The dredging is performed
by means of an appliance consisting of two heavy oaken sticks bound
together in the shape of a cross, from the ends of which hang ropes
upon which are fastened nets with meshes of different sizes. On being
sunk to the bottom by means of a heavy stone, the nets of the dredge
entangle branches of coral, or they are attached by divers, and upon
drawing to the surface the coral can be picked off. The price obtained
for the raw coral is from four to seven dollars per pound, each vessel
securing from three hundred to four hundred pounds in a season.
The industry is almost exclusively in the hands of Italians, although
originally carried on by the French. The latter are said to be striving,
by means of subsidies and in other ways, to regain control of the indus-
try, especially on the Algerian coasts. The production from this region
alone amounts to twenty-two thousand pounds yearly. The cutting
and working of the coral is carried on chiefly in factories in the cities
of Genoa, Leghorn, and Marseilles. The value of the crude coral
varies considerably according to its quality. If the coral polyps have
died before a branch is brought to the surface, the coral turns black,
and its value is thus considerably decreased. On /the shores of Sicily
a large proportion of dead coral is brought up, and the proportion
is continually increasing. The cause is believed to be quantities
of volcanic ash thrown from the neighboring volcanoes, which make
the water too muddy for the polyps. Some of the coral found is con-
siderably worm-eaten, and this sort is highly valued in some parts
of India, although regarded worthless in Europe. The particular shade
of coral most highly valued by Europeans varies from time to time.
At one time the bright red was preferred, then a pale pink, or rose color,
came into fashion, and now the red seems to be most in favor again.
The color, whatever it is, should be uniform to make a piece of coral
of the best quality. The forms into which coral is cut include beads,
buttons, ear-ring drops, cameos, and carvings of various sorts. Polished
pieces of branches an inch or two in length are often worn in bunches,
either as brooches or in the form of bracelets and necklaces. These
were supposed in former times to act as a charm to ward off bad luck
and evil spirits. Coral is especially prized by dark-skinned people,
such as the Italians, Moors, Persians, and Hindoos, because its color
harmonizes well with their complexion. The Chinese also use immense
quantities of it, although the effect in color, as contrasted with that
of the wearer, is less favorable to them.
Precious coral seems to have been known and prized by the Greeks
and Romans. The Greeks called it gorgeia, and believed that it
originated from the blood which dripped from the head of Medusa,
and which becoming hard was planted by sea-nymphs in the sea.
In the Middle Ages precious coral was used in medicine as an as-
tringent, and was given to newly born infants. It was also given
together with a preparation of pearls as a cure for vomiting and
colic. It was supposed to be a heart stimulant and to cure fevers
and poisonings. Hung on fruit-bearing trees it protected them from
hail and blighting winds and gave fertility. It was worn by
children as a preventive against children's diseases, and infants were
supposed to be protected in their sleep by having a piece tied round
To this day the Brahmins and Fakirs of the East place coral upon
their dead to prevent evil spirits taking possession of the corpse, while
in Egypt it is taken internally as a tonic after being treated with lemon
Coral is imitated in celluloid, also by a mixture of marble dust cemented
with glue, and stained with vermilion. Beads of bone and of gypsum
are also stained so as to imitate coral. These imitations can be distin-
guished by chemical and physical characters, true coral having a specific
gravity of 2.6-2.7, and a hardness of nearly 4. It also effervesces
with weak acid, which would not be the case with two of the above
Amorphous substances defined
Apostolic gems -
Australia, diamond fields of
opals of -
sapphires of -
Austrian Yellow diamond -
Black opal - 163
pearl - 216, 220
Blue ground - 83
Blood stone 153, 188
Bombay pearl - - 215
Bone turquois 170
Borneo, diamond fields of 85
Bort - 68
Bowenite - 196
Braganza diamond - - 83, 121
Brazil, agate of - - 154
amethyst of 145
andalusite of - 124
chrysoberyl of - 106
diamond fields of 75
euclase of 104
rock crystal of - 143
topaz of - 121
Brazilian chrysoberyl - - 106
diamond - 142
emerald - 111
sapphire - 111
Brilliant, double - 46
form of - 44
sizes of - 51
British Guiana diamond fields - 86
Bronzite - 169
Burmah, jade of - 165
ruby of - 89
Button pearls - - 213
Cabochon cut 46
Cacholong - 160
Caesium beryl 103
Cairngorm stone - 147
California, diamonds of - 87
tourmaline of - 116
Callainite - 174
Cape chrysolite 193
Cape ruby - 129
Carat defined 50
Carbonado - - - - 68
Cat's-eye - 106, 107,
Ceylon, chrysoberyl of
gem cutting in -
gem mining in
pearl fisheries of
sapphire of -
spinel of -
Ceylon opal -
Colombia, emeralds of
Colors of gems
as seen with the dichroscope
Cutting of gems
artificial production of -
Austrian Yellow -
cleaning of - -
Diamond, combustibility of 66
crystal form of . 67
cutting of - 47
Dresden Green - - 68
Excelsior - 83
Florentine - - -68, 74
Great Mogul - 74
hardness of - - - - 69
Hope Blue - - 68
of India - - 71
Jubilee - 83
Kohinoor - - - - 72
Lake George - - 142
luster of - 68
Matura - 109
mining of - 77
of United States 86
of Ural Mountains - - 85
origin in Brazil - 80
origin in South Africa - 84
Orloff - 73
Pitt - 72
Regent - 72
slaves' - 120
sorting of - - 11, 82
South African - 80
specific gravity of - 69
Victoria - 83
Dichroism - 31
Dichroite - 136
Diopside - 16$
Dioptase - 200
Dispersion - 27
Dispersive power - 27
Disthene - 123
Distortion of crystals 37
Distribution of gems - 7
Double brilliant 46
Double refraction - 29
Doublets - 56
Dresden Green diamond - 68
Effect of heat on color of gems - 14
Emerald 98, 99, 158
confused with jade - - 101
Epidote - 134
Eruptive rocks 6
Essonite - 127
Euxenite - - 140
Excelsior diamond - 83
False amethyst -
Imitation coral -
India, bloodstone of
Flame opal -
moss agate of
Florentine diamond - - 68,
Fluorescence - - 35,
Fool's gold -
distinguished from precious stones
mining of - 8,
mounting of -
nature of -
occurrence of -
valuation of -
Gem gravels - 5, 9
Lake George diamonds
Gibraltar stone -
Golden beryl - 98,
Golden opal -
Great Mogul diamond -
Luster of gems,
Green star stone -
Hardness of gems -
Harlequin opal -
Heavy liquids -
Metallic luster -
Metamorphic rocks -
Hiddenite - -
Methylen iodide -
Honduras, opals of -
Hope Blue diamond
Mining of gems -
Hyacinth 109, 110,
Mounting of gems
Nature of gems
Pitt diamond ...
Nicol prism ...
Occurrence of gems
Pomegranate ruby -
Oily luster -
Precious stones defined
fire - ...
88, 106, 132
Radio-active gems -
Panama pearls ...
Pearl - -
fresh water -
artificial production of -
origin of -
value of -
preservation of -
use in medicine -
Penfield specific gravity balance
Sapphire d'eau -
of Australia -
Sapphire of Siam
Scale of hardness -
Sedimentary rocks -
Semi-precious stones defined
Silky luster -
South Africa, diamonds of
tiger eye of
Spanish topaz -
Spinel ruby -
Star of South Africa diamond
Star of the South diamond
Step cut -
Superstitions regarding gems
Systems of crystallization -
Table of color
Table of hardness
Table of specific gravity
localities of -
of United States
United States, occurrence of
turquois of -
Ural Mountains, aventurine of -
diamond fields of
Valuation of gems
Victoria diamond -
Water sapphire -
14 DAY USE
RETURN TO DESK FROM WHICH BORROWED
This book is due on the last date stamped below, or
on the date to which renewed.
Renewed books are subject to immediate recall.
NOV 9 *64 11 AI
iw* / un - if ^j
AUG 1 2 2006
University of Calif c
THE UNIVERSITY OF CALIFORNIA LIBRARY